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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2019-05-07T02:52:09.0098199+00:00 -->
<!-- Version            : 3.4.7044.22220 -->
<!-- Package ID         : 1a2948946ae741a58fa47f6285fc45d7 -->
<!-- Copyright (c) 2019 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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      <link:roleType roleURI="http://www.nektar.com/20190331/taxonomy/role/DisclosureNetLossPerShareAdditionalInformationDetail" id="Role_DisclosureNetLossPerShareAdditionalInformationDetail">
        <link:definition>100380 - Disclosure - Net Loss Per Share - Additional Information (Detail)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="nktr_LesseeOperatingLeaseLiabilityPaymentsDueYearSix" name="LesseeOperatingLeaseLiabilityPaymentsDueYearSix" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearSix" name="LesseeOperatingLeaseLiabilityPaymentsDueAfterYearSix" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_LesseeOperatingLeaseLiabilityTenantImprovementReimbursements" name="LesseeOperatingLeaseLiabilityTenantImprovementReimbursements" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_AdvancePaymentsToContractManufacturers" name="AdvancePaymentsToContractManufacturers" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_LiabilitiesAndStockholdersEquityDeficitAbstract" name="LiabilitiesAndStockholdersEquityDeficitAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_AccruedContractManufacturingExpenseCurrent" name="AccruedContractManufacturingExpenseCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_AccruedClinicalTrialExpensesCurrent" name="AccruedClinicalTrialExpensesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrentNetOfIssuanceCosts" name="LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrentNetOfIssuanceCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_PreferredStockShareDesignated" name="PreferredStockShareDesignated" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" name="NonCashInterestExpenseRelatedToSaleOfRoyalties" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyaltiesMember" name="NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyaltiesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_LicenseCollaborationAndOtherRevenueMember" name="LicenseCollaborationAndOtherRevenueMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" name="NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesTextBlock" name="LiabilityRelatedToSaleOfPotentialFutureRoyaltiesTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesAbstract" name="LiabilityRelatedToSaleOfPotentialFutureRoyaltiesAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_OrganizationPolicyTextBlock" name="OrganizationPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_AdoptionOfNewAccountingPrinciplePolicyPolicyTextBlock" name="AdoptionOfNewAccountingPrinciplePolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_LiabilityRelatedToSaleOfFutureRoyaltiesPolicyTextBlock" name="LiabilityRelatedToSaleOfFutureRoyaltiesPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" name="CashRestrictedCashCashEquivalentsAndAvailableForSaleInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" name="OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" name="OrganizationAndSummaryOfSignificantAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_CollaborationPartnerMember" name="CollaborationPartnerMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_DebtInvestmentMaximumMaturityPeriod" name="DebtInvestmentMaximumMaturityPeriod" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_DebtInvestmentMaturityDateDescription" name="DebtInvestmentMaturityDateDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_LongTermInvestmentMaturityPeriod" name="LongTermInvestmentMaturityPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_CashAndInvestmentsInMarketableSecuritiesLineItems" name="CashAndInvestmentsInMarketableSecuritiesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_CashAndInvestmentsInMarketableSecuritiesTable" name="CashAndInvestmentsInMarketableSecuritiesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_SevenPointSevenFivePercentSeniorSecuredNotesDueOctoberTwoThousandAndTwentyMember" name="SevenPointSevenFivePercentSeniorSecuredNotesDueOctoberTwoThousandAndTwentyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_SevenPointSevenFivePercentSeniorSecuredNotesRedemptionDatePriorToOctoberFiveTwoThousandAndNineteenMember" name="SevenPointSevenFivePercentSeniorSecuredNotesRedemptionDatePriorToOctoberFiveTwoThousandAndNineteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_SevenPointSevenFivePercentSeniorSecuredNotesRedemptionDateAfterOctoberFiveTwoThousandAndNineteenMember" name="SevenPointSevenFivePercentSeniorSecuredNotesRedemptionDateAfterOctoberFiveTwoThousandAndNineteenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_MinimumCashAndInvestmentsInMarketableSecuritiesToBeMaintained" name="MinimumCashAndInvestmentsInMarketableSecuritiesToBeMaintained" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_AreaOfLeasedSpace" name="AreaOfLeasedSpace" type="num:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="nktr_LeaseCommencementDate" name="LeaseCommencementDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_AdditionalSpaceRequiredToBeLeasedInFuture" name="AdditionalSpaceRequiredToBeLeasedInFuture" type="num:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="nktr_ExtendedLeaseTermStartYear" name="ExtendedLeaseTermStartYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_LeaseExpirationYear" name="LeaseExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_NumberOfConsecutiveFiveYearTermsToExtendLease" name="NumberOfConsecutiveFiveYearTermsToExtendLease" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_ARESanFranciscoNumberOneNineLLCMember" name="ARESanFranciscoNumberOneNineLLCMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_MissionBayLeaseMember" name="MissionBayLeaseMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_ThirdStreetLeaseMember" name="ThirdStreetLeaseMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_KilroyRealtyFinancePartnershipLPMember" name="KilroyRealtyFinancePartnershipLPMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_LeaseTermStartMonthAndYear" name="LeaseTermStartMonthAndYear" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_RemainingSquareFeetOfSpaceExpectedDeliveryYear" name="RemainingSquareFeetOfSpaceExpectedDeliveryYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_NumberOfLeasedSpacesDelivered" name="NumberOfLeasedSpacesDelivered" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_AdditionalOperatingLeaseIncentives" name="AdditionalOperatingLeaseIncentives" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_ProceedsFromSaleOfPotentialFutureRoyaltiesGross" name="ProceedsFromSaleOfPotentialFutureRoyaltiesGross" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_LiabilityRelatedToSaleOfFutureRoyaltiesLineItems" name="LiabilityRelatedToSaleOfFutureRoyaltiesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_LiabilityRelatedToSaleOfFutureRoyaltiesTable" name="LiabilityRelatedToSaleOfFutureRoyaltiesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_PurchaseAndSaleAgreementMember" name="PurchaseAndSaleAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_EstimatedAnnualInterestRateOverLifeOfRoyaltyLiability" name="EstimatedAnnualInterestRateOverLifeOfRoyaltyLiability" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_ProspectiveInterestRatePercentage" name="ProspectiveInterestRatePercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_LicenseCollaborationOtherRevenue" name="LicenseCollaborationOtherRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_LicenseAndCollaborationAgreementsLineItems" name="LicenseAndCollaborationAgreementsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_LicenseAndCollaborationAgreementsTable" name="LicenseAndCollaborationAgreementsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_BaxaltaIncorporatedOrTakedaPLCMember" name="BaxaltaIncorporatedOrTakedaPLCMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_EliLillyAndCompanyMember" name="EliLillyAndCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_AmgenIncMember" name="AmgenIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_OtherPartnerMember" name="OtherPartnerMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_ADYNOVATEMember" name="ADYNOVATEMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_NektarThreeFiveEightMember" name="NektarThreeFiveEightMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_NeulastaMember" name="NeulastaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_UpfrontAndMilestonePaymentsReceivedFromLicenseAgreements" name="UpfrontAndMilestonePaymentsReceivedFromLicenseAgreements" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_LicenseAndCollaborationAgreementsAbstract" name="LicenseAndCollaborationAgreementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_HemophiliaMember" name="HemophiliaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_BMSCollaborationAgreementMember" name="BMSCollaborationAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_NektarTwoOneFourMember" name="NektarTwoOneFourMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_BristolMyersSquibbCompanyMember" name="BristolMyersSquibbCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_OpdivoMember" name="OpdivoMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_OpdivoAndYervoyMember" name="OpdivoAndYervoyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_ClinicalTrialAgreementMember" name="ClinicalTrialAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_SharePurchaseAgreementMember" name="SharePurchaseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_EliLillyMember" name="EliLillyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_NektarThreeFiveEightLicenseMember" name="NektarThreeFiveEightLicenseMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_PhaseOneClinicalDevelopmentMember" name="PhaseOneClinicalDevelopmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_DrugProductDevelopmentMember" name="DrugProductDevelopmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_AnnualSalesLevelMilestoneMember" name="AnnualSalesLevelMilestoneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_AstraZenecaAbMember" name="AstraZenecaAbMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_MOVANTIKAndMOVENTIGMember" name="MOVANTIKAndMOVENTIGMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_AstraZenecaAgreementWithKirinMember" name="AstraZenecaAgreementWithKirinMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="nktr_PotentialDevelopmentAndRegulatoryMilestones" name="PotentialDevelopmentAndRegulatoryMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_ProfitsAndLossesSharingPercentage" name="ProfitsAndLossesSharingPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfSharingInDevelopmentCosts" name="PercentageOfSharingInDevelopmentCosts" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfSharingInProductionCosts" name="PercentageOfSharingInProductionCosts" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfOutOfPocketCostsToBeReimbursedByPartner" name="PercentageOfOutOfPocketCostsToBeReimbursedByPartner" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_CollaborativeArrangementsMaximumAggregateAdditionalCashPaymentsReceivableUponAchievementOfDevelopmentAndRegulatoryMilestones" name="CollaborativeArrangementsMaximumAggregateAdditionalCashPaymentsReceivableUponAchievementOfDevelopmentAndRegulatoryMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_EligibleAdditionalCashPaymentsReceivableUponAchievementOfCertainSalesMilestones" name="EligibleAdditionalCashPaymentsReceivableUponAchievementOfCertainSalesMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_SaleOfStockConsiderationReceived" name="SaleOfStockConsiderationReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_ReimbursementOfExpenses" name="ReimbursementOfExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_AggregateConsiderationReceivedFromAgreements" name="AggregateConsiderationReceivedFromAgreements" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_EstimatedFairValueOfShares" name="EstimatedFairValueOfShares" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_RemainingAmountAllocatedToTransactionPrice" name="RemainingAmountAllocatedToTransactionPrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_PotentialDevelopmentRegulatoryAndSalesMilestones" name="PotentialDevelopmentRegulatoryAndSalesMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_AmountRecognizedForGrantingLicenses" name="AmountRecognizedForGrantingLicenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_PercentageOfSharingInPhaseTwoDevelopmentCosts" name="PercentageOfSharingInPhaseTwoDevelopmentCosts" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfFundingPhaseThreeDevelopmentCostsOnAnIndicationByIndicationBasisBorne" name="PercentageOfFundingPhaseThreeDevelopmentCostsOnAnIndicationByIndicationBasisBorne" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfDevelopmentMilestonesPaymentsToBeReceivedUnderCertainConditions" name="PercentageOfDevelopmentMilestonesPaymentsToBeReceivedUnderCertainConditions" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfDevelopmentMilestonesPaymentsToBeReceivedIfConditionsOccur" name="PercentageOfDevelopmentMilestonesPaymentsToBeReceivedIfConditionsOccur" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_UpfrontAndMilestonePaymentsReceivedUnderLicenseAgreement" name="UpfrontAndMilestonePaymentsReceivedUnderLicenseAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_RegulatoryMilestonesPaymentDescription" name="RegulatoryMilestonesPaymentDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_AmountOfTransactionPriceAllocatedToPerformanceObligation" name="AmountOfTransactionPriceAllocatedToPerformanceObligation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_PaymentsReceivedUnderRightsToSublicenseAgreement" name="PaymentsReceivedUnderRightsToSublicenseAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="nktr_PercentageOfUpfrontPaymentMarketAccessMilestonePaymentsRoyaltiesAndSalesMilestonePaymentsFromSublicenseAgreementRetainedByOurCollaborationPartner" name="PercentageOfUpfrontPaymentMarketAccessMilestonePaymentsRoyaltiesAndSalesMilestonePaymentsFromSublicenseAgreementRetainedByOurCollaborationPartner" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PercentageOfUpfrontPaymentMarketAccessMilestonePaymentsRoyaltiesAndSalesMilestonePayments" name="PercentageOfUpfrontPaymentMarketAccessMilestonePaymentsRoyaltiesAndSalesMilestonePayments" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="nktr_PotentialDevelopmentMilestones" name="PotentialDevelopmentMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="nktr_StockOptionsAndRestrictedStockUnitsMember" name="StockOptionsAndRestrictedStockUnitsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
