

<!-- RR Donnelley Xcelerate Taxonomy Definition Linkbase, based on XBRL 2.1  http://www.edgar-online.com/ -->
<!-- Version: 6.21.0 -->
<!-- Round: 4 -->
<!-- Creation date: 2013-11-11T20:28:54Z -->
<!-- Copyright (c) 2005-2013 R.R. Donnelley & Sons Company All Rights Reserved. -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xbrldt="http://xbrl.org/2005/xbrldt"
  xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DocumentandEntityInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DocumentandEntityInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_StatementOfFinancialPositionClassified" roleURI="http://www.galectintherapeutics.com/taxonomy/role/StatementOfFinancialPositionClassified"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_StatementOfFinancialPositionClassifiedParen" roleURI="http://www.galectintherapeutics.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_StatementOfIncomeAlternative" roleURI="http://www.galectintherapeutics.com/taxonomy/role/StatementOfIncomeAlternative"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_ci-StatementOfShareholdersEquityAndOtherComprehensiveIncome" roleURI="http://www.galectintherapeutics.com/taxonomy/role/StatementOfShareholdersEquityAndOtherComprehensiveIncome"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_StatementOfCashFlowsIndirect" roleURI="http://www.galectintherapeutics.com/taxonomy/role/StatementOfCashFlowsIndirect"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureBasisOfPresentationAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureBasisOfPresentationAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureAccruedExpenses" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureAccruedExpenses"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureStockBasedCompensationExpenseRelatedToCommonStockOptionsCommonStockRestrictedCommonStockAndCommonStockWarrants" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureStockBasedCompensationExpenseRelatedToCommonStockOptionsCommonStockRestrictedCommonStockAndCommonStockWarrants"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureSummaryOfStockOptionActivity" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureSummaryOfStockOptionActivity"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureStockBasedCompensationAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureWeightedAverageAssumptionsUsedToDetermineFairValueOfOptionsGranted" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureWeightedAverageAssumptionsUsedToDetermineFairValueOfOptionsGranted"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureCommonStockWarrantActivity" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommonStockWarrantActivity"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureCommonStockWarrantsAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommonStockWarrantsAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureFairValueOfFinancialInstrumentsAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureDilutiveSharesWhichCouldExistPursuantToExerciseOfOutstandingStockInstrumentsAndWhichWereNotIncludedInCalculation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureDilutiveSharesWhichCouldExistPursuantToExerciseOfOutstandingStockInstrumentsAndWhichWereNotIncludedInCalculation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureCommonStockAndWarrantOfferingAndReverseSplitAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommonStockAndWarrantOfferingAndReverseSplitAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureCommitmentsContingenciesAndLegalProceedingsAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommitmentsContingenciesAndLegalProceedingsAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#DisclosureSubsequentEventsAdditionalInformation" roleURI="http://www.galectintherapeutics.com/taxonomy/role/DisclosureSubsequentEventsAdditionalInformation"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsBasisOfAccounting" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsBasisOfAccounting"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlockTables" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlockTables"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockTables" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockTables"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlockTables" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlockTables"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsFairValueDisclosuresTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsEarningsPerShareTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsEarningsPerShareTextBlockTables" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlockTables"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsStockWarrantsTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsStockWarrantsTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock"/>
  <roleRef xlink:type="simple" xlink:href="galt-20130930.xsd#Role_NotesToFinancialStatementsSubsequentEventsTextBlock" roleURI="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsSubsequentEventsTextBlock"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DocumentandEntityInformation">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_AmendmentFlag" xlink:label="dei_AmendmentFlag"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="dei_CurrentFiscalYearEndDate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="dei_DocumentFiscalPeriodFocus"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_DocumentFiscalYearFocus" xlink:label="dei_DocumentFiscalYearFocus"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_DocumentInformationLineItems" xlink:label="dei_DocumentInformationLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="dei_DocumentPeriodEndDate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_DocumentType" xlink:label="dei_DocumentType"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntitiesTable" xlink:label="dei_EntitiesTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="dei_EntityCentralIndexKey"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="dei_EntityCommonStockSharesOutstanding"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityFilerCategory" xlink:label="dei_EntityFilerCategory"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityRegistrantName" xlink:label="dei_EntityRegistrantName"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_TradingSymbol" xlink:label="dei_TradingSymbol"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntitiesTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentType" order="1.0100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_AmendmentFlag" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentPeriodEndDate" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentFiscalYearFocus" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_DocumentFiscalPeriodFocus" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_TradingSymbol" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityRegistrantName" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCentralIndexKey" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_CurrentFiscalYearEndDate" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityFilerCategory" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_DocumentInformationLineItems" xlink:to="dei_EntityCommonStockSharesOutstanding" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="dei_EntitiesTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/StatementOfFinancialPositionClassified">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="us-gaap_AccountsPayableCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="us-gaap_AccruedLiabilitiesCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="us-gaap_AdditionalPaidInCapital"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="us-gaap_AssetsAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="us-gaap_AssetsCurrentAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="us-gaap_CommitmentsAndContingencies"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DevelopmentStageEnterpriseDeficitAccumulatedDuringDevelopmentStage" xlink:label="us-gaap_DevelopmentStageEnterpriseDeficitAccumulatedDuringDevelopmentStage"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DividendsPayableCurrent" xlink:label="us-gaap_DividendsPayableCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="us-gaap_LiabilitiesCurrentAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="us-gaap_OtherLiabilitiesNoncurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="us-gaap_PreferredStockValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBOnePreferredStockMember" xlink:label="galt_SeriesBOnePreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBTwoPreferredStockMember" xlink:label="galt_SeriesBTwoPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="us-gaap_SeriesCPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="us-gaap_StockholdersEquityAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UndesignatedCapitalStockValue" xlink:label="galt_UndesignatedCapitalStockValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_AssetsCurrentAbstract" order="1.2700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="1.2800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherAssetsNoncurrent" order="1.2900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill" order="1.3000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_Assets" order="1.3100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AssetsCurrent" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBOnePreferredStockMember" order="1.2400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBTwoPreferredStockMember" order="1.2500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="1.2600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_OtherLiabilitiesNoncurrent" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_Liabilities" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_CommitmentsAndContingencies" order="1.2000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" order="1.2100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract" order="1.2200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity" order="1.2300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_AccountsPayableCurrent" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_AccruedLiabilitiesCurrent" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_DividendsPayableCurrent" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrent" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AssetsAbstract" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="galt_UndesignatedCapitalStockValue" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_PreferredStockValue" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_CommonStockValue" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_AdditionalPaidInCapital" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_DevelopmentStageEnterpriseDeficitAccumulatedDuringDevelopmentStage" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquity" order="1.1300" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="us-gaap_PreferredStockSharesAuthorized"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="us-gaap_PreferredStockSharesIssued"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="us-gaap_PreferredStockSharesOutstanding"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBOnePreferredStockMember" xlink:label="galt_SeriesBOnePreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBTwoPreferredStockMember" xlink:label="galt_SeriesBTwoPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="us-gaap_SeriesCPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityLiquidationPreference" xlink:label="us-gaap_TemporaryEquityLiquidationPreference"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityRedemptionValue" xlink:label="us-gaap_TemporaryEquityRedemptionValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesAuthorized" xlink:label="us-gaap_TemporaryEquitySharesAuthorized"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesIssued" xlink:label="us-gaap_TemporaryEquitySharesIssued"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding" xlink:label="us-gaap_TemporaryEquitySharesOutstanding"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UndesignatedCapitalStockNoParValue" xlink:label="galt_UndesignatedCapitalStockNoParValue"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UndesignatedCapitalStockSharesAuthorized" xlink:label="galt_UndesignatedCapitalStockSharesAuthorized"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UndesignatedCapitalStockSharesOutstanding" xlink:label="galt_UndesignatedCapitalStockSharesOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBOnePreferredStockMember" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBTwoPreferredStockMember" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TemporaryEquitySharesAuthorized" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TemporaryEquitySharesIssued" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TemporaryEquitySharesOutstanding" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TemporaryEquityRedemptionValue" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TemporaryEquityLiquidationPreference" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_UndesignatedCapitalStockNoParValue" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_UndesignatedCapitalStockSharesAuthorized" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_UndesignatedCapitalStockSharesOutstanding" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesAuthorized" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesIssued" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesOutstanding" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="2.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/StatementOfIncomeAlternative">
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AdjustmentForModificationOfWarrants" xlink:label="galt_AdjustmentForModificationOfWarrants"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted" xlink:label="us-gaap_EarningsPerShareBasicAndDiluted"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="us-gaap_FairValueAdjustmentOfWarrants"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="us-gaap_GeneralAndAdministrativeExpense"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="us-gaap_InvestmentIncomeInterest"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="us-gaap_NonoperatingIncomeExpense"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NonoperatingIncomeExpenseAbstract" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="us-gaap_OperatingExpenses"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="us-gaap_OperatingExpensesAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherNonoperatingIncome" xlink:label="us-gaap_OtherNonoperatingIncome"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockAccretionOfRedemptionDiscount" xlink:label="us-gaap_PreferredStockAccretionOfRedemptionDiscount"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact" xlink:label="us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="us-gaap_ResearchAndDevelopmentExpense"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UnrealizedGainLossInDebtInstrumentFairValue" xlink:label="galt_UnrealizedGainLossInDebtInstrumentFairValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:label="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_InvestmentIncomeInterest" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_InterestExpense" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="galt_UnrealizedGainLossInDebtInstrumentFairValue" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_FairValueAdjustmentOfWarrants" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_OtherNonoperatingIncome" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_NonoperatingIncomeExpense" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_ResearchAndDevelopmentExpense" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_GeneralAndAdministrativeExpense" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpenses" order="1.2000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OperatingExpensesAbstract" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OperatingIncomeLoss" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NonoperatingIncomeExpenseAbstract" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLoss" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockDividendsIncomeStatementImpact" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockAccretionOfRedemptionDiscount" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_AdjustmentForModificationOfWarrants" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EarningsPerShareBasicAndDiluted" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/StatementOfShareholdersEquityAndOtherComprehensiveIncome">
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AccretionOfRedeemableConvertiblePreferredStock" xlink:label="galt_AccretionOfRedeemableConvertiblePreferredStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedDeficitDuringDevelopmentStageMember" xlink:label="us-gaap_AccumulatedDeficitDuringDevelopmentStageMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AdjustmentForModificationOfWarrants" xlink:label="galt_AdjustmentForModificationOfWarrants"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DividendsPreferredStock" xlink:label="us-gaap_DividendsPreferredStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockDividendsShares" xlink:label="us-gaap_PreferredStockDividendsShares"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="us-gaap_SeriesAPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBOnePreferredStockMember" xlink:label="galt_SeriesBOnePreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBTwoPreferredStockMember" xlink:label="galt_SeriesBTwoPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="us-gaap_SeriesCPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="us-gaap_SharesOutstanding"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_StockIssuedDuringPeriodSharesStockWarrantsExercised" xlink:label="galt_StockIssuedDuringPeriodSharesStockWarrantsExercised"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_StockIssuedDuringPeriodValueStockWarrantsExercised" xlink:label="galt_StockIssuedDuringPeriodValueStockWarrantsExercised"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityAccretionToRedemptionValueAdjustment" xlink:label="us-gaap_TemporaryEquityAccretionToRedemptionValueAdjustment"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" order="1.2800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBOnePreferredStockMember" order="1.2900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBTwoPreferredStockMember" order="1.3000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="1.3100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="galt_SeriesBOnePreferredStockMember" order="1.2100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="galt_SeriesBTwoPreferredStockMember" order="1.2200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="1.2300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" order="1.2400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="1.2500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" order="1.2600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedDeficitDuringDevelopmentStageMember" order="1.2700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharesOutstanding" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquity" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_AccretionOfRedeemableConvertiblePreferredStock" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TemporaryEquityAccretionToRedemptionValueAdjustment" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockDividendsShares" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DividendsPreferredStock" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_StockIssuedDuringPeriodSharesStockWarrantsExercised" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_StockIssuedDuringPeriodValueStockWarrantsExercised" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_AdjustmentForModificationOfWarrants" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLoss" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="3.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/StatementOfCashFlowsIndirect">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ConversionOfAccruedLiabilitiesToCommonStock" xlink:label="galt_ConversionOfAccruedLiabilitiesToCommonStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="us-gaap_DebtConversionConvertedInstrumentAmount1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtConversionOriginalDebtAmount1" xlink:label="us-gaap_DebtConversionOriginalDebtAmount1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="us-gaap_DepreciationAndAmortization"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="us-gaap_FairValueAdjustmentOfWarrants"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCash" xlink:label="us-gaap_IncreaseDecreaseInRestrictedCash"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestPaid" xlink:label="us-gaap_InterestPaid"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_IssuanceOfEquityWarrantsInConnectionWithEquityOfferings" xlink:label="galt_IssuanceOfEquityWarrantsInConnectionWithEquityOfferings"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_IssuanceOfWarrantsToInduceConversionOfNotesPayable" xlink:label="galt_IssuanceOfWarrantsToInduceConversionOfNotesPayable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaidInKindInterest" xlink:label="us-gaap_PaidInKindInterest"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets" xlink:label="us-gaap_PaymentsToAcquireProductiveAssets"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromConvertibleDebt" xlink:label="us-gaap_ProceedsFromConvertibleDebt"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" xlink:label="us-gaap_ProceedsFromIssuanceOfRedeemableConvertiblePreferredStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:label="us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ProceedsFromStockOptionAndWarrantExercises" xlink:label="galt_ProceedsFromStockOptionAndWarrantExercises"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RepaymentsOfConvertibleDebt" xlink:label="us-gaap_RepaymentsOfConvertibleDebt"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="us-gaap_SeriesAPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBOnePreferredStockMember" xlink:label="galt_SeriesBOnePreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeriesBTwoPreferredStockMember" xlink:label="galt_SeriesBTwoPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="us-gaap_SeriesCPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssued1" xlink:label="us-gaap_StockIssued1"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SupplementalDividendsOnConvertiblePreferredStock" xlink:label="galt_SupplementalDividendsOnConvertiblePreferredStock"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UnrealizedGainLossInDebtInstrumentFairValue" xlink:label="galt_UnrealizedGainLossInDebtInstrumentFairValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_DepreciationAndAmortization" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_ShareBasedCompensation" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_PaidInKindInterest" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="galt_UnrealizedGainLossInDebtInstrumentFairValue" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_FairValueAdjustmentOfWarrants" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="galt_IssuanceOfEquityWarrantsInConnectionWithEquityOfferings" order="1.2000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="galt_ConversionOfAccruedLiabilitiesToCommonStock" order="1.2100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="us-gaap_DebtConversionOriginalDebtAmount1" order="1.2200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="us-gaap_DebtConversionConvertedInstrumentAmount1" order="1.2300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="galt_SupplementalDividendsOnConvertiblePreferredStock" order="1.2400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="galt_IssuanceOfWarrantsToInduceConversionOfNotesPayable" order="1.2500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="us-gaap_StockIssued1" order="1.2600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" order="1.4200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBOnePreferredStockMember" order="1.4300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_SeriesBTwoPreferredStockMember" order="1.4400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="1.4500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" order="1.3100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" order="1.3200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities" order="1.3300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="1.3400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" order="1.3500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" order="1.3600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromConvertibleDebt" order="1.3700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_RepaymentsOfConvertibleDebt" order="1.3800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="galt_ProceedsFromStockOptionAndWarrantExercises" order="1.3900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" order="1.4000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" order="1.4100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" order="1.2700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInRestrictedCash" order="1.2800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquireProductiveAssets" order="1.2900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" order="1.3000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetIncomeLoss" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_InterestPaid" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="2.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureBasisOfPresentationAdditionalInformation">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_2"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_BasisOfPresentationLineItems" xlink:label="galt_BasisOfPresentationLineItems"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_BasisOfPresentationTable" xlink:label="galt_BasisOfPresentationTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_MarketSaleAgreementMember" xlink:label="galt_MarketSaleAgreementMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="us-gaap_ProceedsFromWarrantExercises"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharePrice" xlink:label="us-gaap_SharePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_StockIssuedDuringPeriodSharesStockWarrantsExercised" xlink:label="galt_StockIssuedDuringPeriodSharesStockWarrantsExercised"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="galt_MarketSaleAgreementMember" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="galt_BasisOfPresentationTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_ProceedsFromWarrantExercises" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="galt_StockIssuedDuringPeriodSharesStockWarrantsExercised" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_SharePrice" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_BasisOfPresentationLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_BasisOfPresentationTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_BasisOfPresentationTable" xlink:to="us-gaap_SubsequentEventTypeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_BasisOfPresentationTable" xlink:to="us-gaap_TypeOfArrangementAxis" order="3.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_2" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureAccruedExpenses">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="us-gaap_AccruedLiabilitiesCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedProfessionalFeesCurrent" xlink:label="us-gaap_AccruedProfessionalFeesCurrent"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AccruedSeparationAgreement" xlink:label="galt_AccruedSeparationAgreement"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:label="galt_ScheduleOfAccruedLiabilitiesLineItems"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ScheduleOfAccruedLiabilitiesTable" xlink:label="galt_ScheduleOfAccruedLiabilitiesTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:to="galt_ScheduleOfAccruedLiabilitiesTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:to="us-gaap_AccruedProfessionalFeesCurrent" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:to="galt_AccruedSeparationAgreement" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrent" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ScheduleOfAccruedLiabilitiesLineItems" xlink:to="us-gaap_AccruedLiabilitiesCurrent" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_ScheduleOfAccruedLiabilitiesTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureStockBasedCompensationExpenseRelatedToCommonStockOptionsCommonStockRestrictedCommonStockAndCommonStockWarrants">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ShareBasedCompensation" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_ResearchAndDevelopmentExpenseMember" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_GeneralAndAdministrativeExpenseMember" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="us-gaap_IncomeStatementLocationAxis" order="2.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureSummaryOfStockOptionActivity">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" order="1.1200" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformation">
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AdditionalShareBasedCompensationExpenseRelatedToModifiedStockOptions" xlink:label="galt_AdditionalShareBasedCompensationExpenseRelatedToModifiedStockOptions"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AmendmentMember" xlink:label="galt_AmendmentMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationTermInCertainCases" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationTermInCertainCases"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VestingAxis" xlink:label="us-gaap_VestingAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VestingDomain" xlink:label="us-gaap_VestingDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VestingDomain" xlink:label="us-gaap_VestingDomain_2"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_VestingAxis" order="3.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationTermInCertainCases" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_AdditionalShareBasedCompensationExpenseRelatedToModifiedStockOptions" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_VestingAxis" xlink:to="us-gaap_VestingDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_VestingAxis" xlink:to="us-gaap_VestingDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VestingDomain" xlink:to="galt_AmendmentMember" order="1.1000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureWeightedAverageAssumptionsUsedToDetermineFairValueOfOptionsGranted">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" order="1.0500" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommonStockWarrantActivity">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisesInPeriod" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisesInPeriod"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract" xlink:label="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisesInPeriod" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisesInPeriodWeightedAverageExercisePrice" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresInPeriodWeightedAverageExercisePrice" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageExercisePriceAbstract" order="1.0300" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommonStockWarrantsAdditionalInformation">
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AfterModificationMember" xlink:label="galt_AfterModificationMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_BeforeModificationMember" xlink:label="galt_BeforeModificationMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ClassATwoWarrantsMember" xlink:label="galt_ClassATwoWarrantsMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ClassBWarrantsMember" xlink:label="galt_ClassBWarrantsMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ClassOfWarrantOrRightExpirationDateExtensionPeriod" xlink:label="galt_ClassOfWarrantOrRightExpirationDateExtensionPeriod"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="us-gaap_MaximumMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="us-gaap_MinimumMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_NumberOfWarrantsExercise" xlink:label="galt_NumberOfWarrantsExercise"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="us-gaap_RangeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="us-gaap_RangeMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="us-gaap_ScenarioUnspecifiedDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="us-gaap_ScenarioUnspecifiedDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="us-gaap_StatementScenarioAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_WarrantExpense" xlink:label="galt_WarrantExpense"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WarrantMember" xlink:label="us-gaap_WarrantMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_WarrantToPurchaseCommonStock" xlink:label="galt_WarrantToPurchaseCommonStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_ClassBWarrantsMember" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="galt_ClassATwoWarrantsMember" order="1.2300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="1.2100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MaximumMember" order="1.2400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="galt_BeforeModificationMember" order="1.2000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="galt_AfterModificationMember" order="1.2500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="3.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_StatementScenarioAxis" order="4.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_RangeAxis" order="5.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_WarrantToPurchaseCommonStock" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_ClassOfWarrantOrRightExpirationDateExtensionPeriod" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_WarrantExpense" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="galt_NumberOfWarrantsExercise" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensation" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_WarrantMember" order="1.2200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_2" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformation">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="us-gaap_AssetsFairValueDisclosure"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_FairValueOfFinancialInstrumentsLineItems" xlink:label="galt_FairValueOfFinancialInstrumentsLineItems"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_FairValueOfFinancialInstrumentsTable" xlink:label="galt_FairValueOfFinancialInstrumentsTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="us-gaap_MoneyMarketFundsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="galt_FairValueOfFinancialInstrumentsLineItems" xlink:to="galt_FairValueOfFinancialInstrumentsTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_FairValueOfFinancialInstrumentsLineItems" xlink:to="us-gaap_AssetsFairValueDisclosure" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_FairValueOfFinancialInstrumentsTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_FairValueOfFinancialInstrumentsTable" xlink:to="us-gaap_InvestmentTypeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_FairValueOfFinancialInstrumentsTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="3.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_MoneyMarketFundsMember" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureDilutiveSharesWhichCouldExistPursuantToExerciseOfOutstandingStockInstrumentsAndWhichWereNotIncludedInCalculation">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockCompensationPlanMember" xlink:label="us-gaap_StockCompensationPlanMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WarrantMember" xlink:label="us-gaap_WarrantMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_WarrantMember" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_StockCompensationPlanMember" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" order="2.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommonStockAndWarrantOfferingAndReverseSplitAdditionalInformation">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ClassOfWarrantOrRightIssuableWithEachNewShareOfCommonStock" xlink:label="galt_ClassOfWarrantOrRightIssuableWithEachNewShareOfCommonStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ExpirationPeriodOfAgreements" xlink:label="galt_ExpirationPeriodOfAgreements"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedTerm" xlink:label="us-gaap_FairValueAssumptionsExpectedTerm"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:label="us-gaap_FairValueAssumptionsRiskFreeInterestRate"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsWeightedAverageVolatilityRate" xlink:label="us-gaap_FairValueAssumptionsWeightedAverageVolatilityRate"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_GrossProceedsFromIssuanceOfCommonStockAndWarrants" xlink:label="galt_GrossProceedsFromIssuanceOfCommonStockAndWarrants"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember_2"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_IssuanceOfCommonStockAndWarrantsShares" xlink:label="galt_IssuanceOfCommonStockAndWarrantsShares"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_IssuanceOfWarrantsPricePerShare" xlink:label="galt_IssuanceOfWarrantsPricePerShare"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_IssuanceOfWarrantsValue" xlink:label="galt_IssuanceOfWarrantsValue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_NumberOfCommonStockPerUnit" xlink:label="galt_NumberOfCommonStockPerUnit"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PrivatePlacementMember" xlink:label="us-gaap_PrivatePlacementMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_PublicOfferingNetPricePerShare" xlink:label="galt_PublicOfferingNetPricePerShare"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_StockholdersEquityLineItems" xlink:label="galt_StockholdersEquityLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:label="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_StockholdersEquityTable" xlink:label="galt_StockholdersEquityTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_UnderwritersExerciseOfPublicOfferingOverAllotmentShares" xlink:label="galt_UnderwritersExerciseOfPublicOfferingOverAllotmentShares"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_WarrantExpirationDate" xlink:label="galt_WarrantExpirationDate"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_WarrantOneMember" xlink:label="galt_WarrantOneMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_WarrantsPricePerShare" xlink:label="galt_WarrantsPricePerShare"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_WarrantTwoMember" xlink:label="galt_WarrantTwoMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_PrivatePlacementMember" order="1.2400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="galt_WarrantOneMember" order="1.2300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="galt_WarrantTwoMember" order="1.2500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_StockholdersEquityTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_NumberOfCommonStockPerUnit" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_ClassOfWarrantOrRightIssuableWithEachNewShareOfCommonStock" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_ExpirationPeriodOfAgreements" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_UnderwritersExerciseOfPublicOfferingOverAllotmentShares" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_PublicOfferingNetPricePerShare" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_WarrantExpirationDate" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_IssuanceOfCommonStockAndWarrantsShares" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_WarrantsPricePerShare" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_GrossProceedsFromIssuanceOfCommonStockAndWarrants" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOrSaleOfEquity" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_IssuanceOfWarrantsValue" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="galt_IssuanceOfWarrantsPricePerShare" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_FairValueAssumptionsExpectedTerm" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_FairValueAssumptionsWeightedAverageVolatilityRate" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_FairValueAssumptionsRiskFreeInterestRate" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" order="1.2000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="1.2100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_StockholdersEquityLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="1.2200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_StockholdersEquityTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_StockholdersEquityTable" xlink:to="us-gaap_AwardTypeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_StockholdersEquityTable" xlink:to="us-gaap_InvestmentTypeAxis" order="3.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureCommitmentsContingenciesAndLegalProceedingsAdditionalInformation">
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AccruedInterestMember" xlink:label="galt_AccruedInterestMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AccruedSeparationAgreement" xlink:label="galt_AccruedSeparationAgreement"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_CollaborationAgreementResearchAndDevelopmentThatWillBeFunded" xlink:label="galt_CollaborationAgreementResearchAndDevelopmentThatWillBeFunded"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_CommitmentsAndContingenciesLineItems" xlink:label="galt_CommitmentsAndContingenciesLineItems"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_CommitmentsAndContingenciesTable" xlink:label="galt_CommitmentsAndContingenciesTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ComponentsOfCommonStockAxis" xlink:label="galt_ComponentsOfCommonStockAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ComponentsOfCommonStockByTypeDomain" xlink:label="galt_ComponentsOfCommonStockByTypeDomain"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ComponentsOfCommonStockByTypeDomain" xlink:label="galt_ComponentsOfCommonStockByTypeDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="us-gaap_ConversionOfStockSharesConverted1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConversionOfStockSharesIssued1" xlink:label="us-gaap_ConversionOfStockSharesIssued1"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_DividendEquivalentRights" xlink:label="galt_DividendEquivalentRights"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_DrugDiscoveryProgramMember" xlink:label="galt_DrugDiscoveryProgramMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_LawsuitDamageClaim" xlink:label="galt_LawsuitDamageClaim"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_MaximumDevelopmentBudget" xlink:label="galt_MaximumDevelopmentBudget"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_MinimumCompanyMarketCapitalization" xlink:label="galt_MinimumCompanyMarketCapitalization"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="us-gaap_MinimumMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_NoticePeriodForTerminationOfAgreement" xlink:label="galt_NoticePeriodForTerminationOfAgreement"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_NoticePeriodToCureBreachOfAgreement" xlink:label="galt_NoticePeriodToCureBreachOfAgreement"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_NumberOfRightDeclaredAsDividendDistributionForEachOutstandingShareOfCommonStock" xlink:label="galt_NumberOfRightDeclaredAsDividendDistributionForEachOutstandingShareOfCommonStock"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_OrganizationalAndSeparationRelatedCharges" xlink:label="galt_OrganizationalAndSeparationRelatedCharges"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireInProcessResearchAndDevelopment" xlink:label="us-gaap_PaymentsToAcquireInProcessResearchAndDevelopment"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockDividendRatePercentage" xlink:label="us-gaap_PreferredStockDividendRatePercentage"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_PrincipalSharesMember" xlink:label="galt_PrincipalSharesMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="us-gaap_RangeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="us-gaap_RangeMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="us-gaap_RangeMember_2"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_RecognizedExpensesRelatedToAgreementForServicesPerformed" xlink:label="galt_RecognizedExpensesRelatedToAgreementForServicesPerformed"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RoyaltyRevenue" xlink:label="us-gaap_RoyaltyRevenue"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SeriesCPreferredStockMember" xlink:label="us-gaap_SeriesCPreferredStockMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ServiceAgreementsExpirationDate" xlink:label="galt_ServiceAgreementsExpirationDate"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_SeverancePaymentPeriod" xlink:label="galt_SeverancePaymentPeriod"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityRedemptionValue" xlink:label="us-gaap_TemporaryEquityRedemptionValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesCPreferredStockMember" order="1.2800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_CommonStockMember" order="1.3000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_CommitmentsAndContingenciesTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_ServiceAgreementsExpirationDate" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_MaximumDevelopmentBudget" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_RecognizedExpensesRelatedToAgreementForServicesPerformed" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_NoticePeriodForTerminationOfAgreement" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_NoticePeriodToCureBreachOfAgreement" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_CollaborationAgreementResearchAndDevelopmentThatWillBeFunded" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_PaymentsToAcquireInProcessResearchAndDevelopment" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_AccruedSeparationAgreement" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_EquityMethodInvestments" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_RoyaltyRevenue" order="1.1300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" order="1.1400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_MinimumCompanyMarketCapitalization" order="1.1500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_SeverancePaymentPeriod" order="1.1600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_OrganizationalAndSeparationRelatedCharges" order="1.1700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_LawsuitDamageClaim" order="1.1800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_ConversionOfStockSharesConverted1" order="1.1900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_ConversionOfStockSharesIssued1" order="1.2000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_DividendEquivalentRights" order="1.2100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_PreferredStockDividendRatePercentage" order="1.2200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="galt_NumberOfRightDeclaredAsDividendDistributionForEachOutstandingShareOfCommonStock" order="1.2300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_TemporaryEquityRedemptionValue" order="1.2400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_CommitmentsAndContingenciesTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_CommitmentsAndContingenciesTable" xlink:to="us-gaap_RangeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_CommitmentsAndContingenciesTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="3.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_CommitmentsAndContingenciesTable" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" order="4.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_CommitmentsAndContingenciesTable" xlink:to="galt_ComponentsOfCommonStockAxis" order="5.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="galt_CommitmentsAndContingenciesTable" xlink:to="us-gaap_SubsequentEventTypeAxis" order="6.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="galt_ComponentsOfCommonStockAxis" xlink:to="galt_ComponentsOfCommonStockByTypeDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="galt_ComponentsOfCommonStockAxis" xlink:to="galt_ComponentsOfCommonStockByTypeDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ComponentsOfCommonStockByTypeDomain" xlink:to="galt_PrincipalSharesMember" order="1.2900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="galt_ComponentsOfCommonStockByTypeDomain" xlink:to="galt_AccruedInterestMember" order="1.3100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="us-gaap_RangeMember_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RangeMember" xlink:to="us-gaap_MinimumMember" order="1.2600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:to="galt_DrugDiscoveryProgramMember" order="1.2500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" order="1.2700" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/DisclosureSubsequentEventsAdditionalInformation">
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_AggregateOfferingPrice" xlink:label="galt_AggregateOfferingPrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ClassATwoWarrantsMember" xlink:label="galt_ClassATwoWarrantsMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_2"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_CommissionsAsPercentageOfGrossOfferingProceeds" xlink:label="galt_CommissionsAsPercentageOfGrossOfferingProceeds"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ExerciseOfPreferredStockWarrantsShares" xlink:label="galt_ExerciseOfPreferredStockWarrantsShares"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_MarketSaleAgreementMember" xlink:label="galt_MarketSaleAgreementMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharePrice" xlink:label="us-gaap_SharePrice"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="us-gaap_SubsequentEventLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="us-gaap_SubsequentEventTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="galt_MarketSaleAgreementMember" order="1.1200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_2" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="galt_ClassATwoWarrantsMember" order="1.1100" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_SubsequentEventTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="galt_ExerciseOfPreferredStockWarrantsShares" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOrSaleOfEquity" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="galt_AggregateOfferingPrice" order="1.0500" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="galt_CommissionsAsPercentageOfGrossOfferingProceeds" order="1.0600" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" order="1.0700" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_SharePrice" order="1.0800" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="1.0900" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_SubsequentEventTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_SubsequentEventTable" xlink:to="us-gaap_SubsequentEventTypeAxis" order="2.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_SubsequentEventTable" xlink:to="us-gaap_ClassOfWarrantOrRightAxis" order="3.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_SubsequentEventTable" xlink:to="us-gaap_TypeOfArrangementAxis" order="4.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" order="1.1000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsBasisOfAccounting">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BasisOfAccounting" xlink:label="us-gaap_BasisOfAccounting"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_BasisOfAccounting" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlockTables">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:label="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockTables">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" order="1.0300" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" order="1.0400" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityNoteDisclosureTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlockTables">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_ScheduleOfStockholdersEquityNoteWarrantsAndCommonStockActivityTableTextBlock" xlink:label="galt_ScheduleOfStockholdersEquityNoteWarrantsAndCommonStockActivityTableTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_ScheduleOfStockholdersEquityNoteWarrantsAndCommonStockActivityTableTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueDisclosuresTextBlock" xlink:label="us-gaap_FairValueDisclosuresTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueDisclosuresTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EarningsPerShareTextBlock" xlink:label="us-gaap_EarningsPerShareTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EarningsPerShareTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlockTables">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsStockWarrantsTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="galt-20130930.xsd#galt_StockWarrantsTextBlock" xlink:label="galt_StockWarrantsTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="galt_StockWarrantsTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.galectintherapeutics.com/taxonomy/role/NotesToFinancialStatementsSubsequentEventsTextBlock">
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventsTextBlock" xlink:label="us-gaap_SubsequentEventsTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="1.0000" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="100.0000" xbrldt:closed="true" xbrldt:contextElement="segment" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SubsequentEventsTextBlock" order="1.0200" priority="2" use="optional"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="dei_LegalEntityAxis" order="1.0000" priority="2" use="optional"/>
  </definitionLink>
</linkbase>




