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  <xs:element id="nktr_TransactionCostsRelatedToSaleOfPotentialFutureRoyalties" abstract="false" name="TransactionCostsRelatedToSaleOfPotentialFutureRoyalties" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_TwoThousandSeventeenPerformanceIncentivePlanMember" abstract="true" name="TwoThousandSeventeenPerformanceIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_TaxPositionsRelatedToCurrentYearAbstract" abstract="true" name="TaxPositionsRelatedToCurrentYearAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_ObligationsUnderDirectorAndOfficerIndemnificationsPerIncident" abstract="false" name="ObligationsUnderDirectorAndOfficerIndemnificationsPerIncident" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_EliLillyAndCompanyMember" abstract="true" name="EliLillyAndCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_PfizerMember" abstract="true" name="PfizerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_Nektar214Member" abstract="true" name="Nektar214Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_ScheduleOfLeasesTable" abstract="true" name="ScheduleOfLeasesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="nktr_UpfrontAndMilestonePaymentsReceivedUnderLicenseAgreement" abstract="false" name="UpfrontAndMilestonePaymentsReceivedUnderLicenseAgreement" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_PercentageOfSharingInPhaseTwoDevelopmentCosts" abstract="false" name="PercentageOfSharingInPhaseTwoDevelopmentCosts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nktr_EmployeeMember" abstract="true" name="EmployeeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_ProgramTerminationMember" abstract="true" name="ProgramTerminationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_LiabilityRelatedToTheSaleOfFutureRoyaltiesRollForward" abstract="true" name="LiabilityRelatedToTheSaleOfFutureRoyaltiesRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_CashAndNonCashRoyaltiesMember" abstract="true" name="CashAndNonCashRoyaltiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" abstract="true" name="OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrent" abstract="false" name="LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_NoncashInvestingAndFinancingActivitiesAccountsReceivableRecognizedInExchangeForLongTermLiabilities" abstract="false" name="NoncashInvestingAndFinancingActivitiesAccountsReceivableRecognizedInExchangeForLongTermLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_CashAndInvestmentsInMarketableSecuritiesTable" abstract="true" name="CashAndInvestmentsInMarketableSecuritiesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="nktr_BristolMyersSquibbCollaborationAgreementMember" abstract="true" name="BristolMyersSquibbCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_ProgramTerminationAdvancePaymntToContractManyfacturersMember" abstract="true" name="ProgramTerminationAdvancePaymntToContractManyfacturersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_MeasurementInputMarketParticipantSubtenantBorrowingRateMember" abstract="true" name="MeasurementInputMarketParticipantSubtenantBorrowingRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_OrganizationPolicyTextBlock" abstract="false" name="OrganizationPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="nktr_LicenseAndCollaborationAgreementsLineItems" abstract="true" name="LicenseAndCollaborationAgreementsLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_UpfrontAndMilestonePaymentsReceivedFromLicenseAgreements" abstract="false" name="UpfrontAndMilestonePaymentsReceivedFromLicenseAgreements" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_TaxPositionsRelatedToPriorYearsAbstract" abstract="true" name="TaxPositionsRelatedToPriorYearsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_PotentialDevelopmentMilestones" abstract="false" name="PotentialDevelopmentMilestones" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_Nektar358Member" abstract="true" name="Nektar358Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_ProceedsFromSaleOfPotentialFutureRoyaltiesGross" abstract="false" name="ProceedsFromSaleOfPotentialFutureRoyaltiesGross" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_MilestoneOneMember" abstract="true" name="MilestoneOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_DepreciablePropertyPlantAndEquipmentNet" abstract="false" name="DepreciablePropertyPlantAndEquipmentNet" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_EffectiveIncomeTaxRateReconciliationExpirationOfNetOperatingLossCarryforwards" abstract="false" name="EffectiveIncomeTaxRateReconciliationExpirationOfNetOperatingLossCarryforwards" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_UnrecognizedTaxBenefitsPeriodIncreaseDecreaseReasonablePeriodOfChange" abstract="false" name="UnrecognizedTaxBenefitsPeriodIncreaseDecreaseReasonablePeriodOfChange" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nktr_DeferredTaxAssetsLiabilityRelatedToTheSaleOfFutureRoyalties" abstract="false" name="DeferredTaxAssetsLiabilityRelatedToTheSaleOfFutureRoyalties" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_DeferredTaxAssetsLeaseLiability" abstract="false" name="DeferredTaxAssetsLeaseLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_CollaborativeArrangementSuccessBasedPaymentsAmount" abstract="false" name="CollaborativeArrangementSuccessBasedPaymentsAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_OpdivoMember" abstract="true" name="OpdivoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_PreferredStockShareDesignated" abstract="false" name="PreferredStockShareDesignated" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="nktr_EffectiveIncomeTaxRateReconciliationNonDeductibleExpenseForLiabilityRelatedSaleOfFutureRoyaltiesAmount" abstract="false" name="EffectiveIncomeTaxRateReconciliationNonDeductibleExpenseForLiabilityRelatedSaleOfFutureRoyaltiesAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_ImpairmentOfEquipmentFromTerminatedProgram" abstract="false" name="ImpairmentOfEquipmentFromTerminatedProgram" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_CollaborativeArrangementCommittedFunding" abstract="false" name="CollaborativeArrangementCommittedFunding" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_PurchaseAndSaleAgreementMember" abstract="true" name="PurchaseAndSaleAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_SharePurchaseAgreementMember" abstract="true" name="SharePurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_LiabilitiesOnSaleOfFutureRoyaltiesUnamortizedTransactionCosts" abstract="false" name="LiabilitiesOnSaleOfFutureRoyaltiesUnamortizedTransactionCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_SecuritiesRelatedClaimsMember" abstract="true" name="SecuritiesRelatedClaimsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_GainLossONRevaluationOfLiabilitiesRelatedToTheSaleOfFutureRoyaltiesGross" abstract="false" name="GainLossONRevaluationOfLiabilitiesRelatedToTheSaleOfFutureRoyaltiesGross" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_NumberOfConsecutiveTermsToExtendLease" abstract="false" name="NumberOfConsecutiveTermsToExtendLease" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nktr_EmployeeStockPurchasePlanMember" abstract="true" name="EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_AccountsReceivableAndSignificantCustomerConcentrationsPolicyTextBlock" abstract="false" name="AccountsReceivableAndSignificantCustomerConcentrationsPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="nktr_InvestmentsWeightedAverageMaturityPeriod" abstract="false" name="InvestmentsWeightedAverageMaturityPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nktr_BempegaldesleukinMember" abstract="true" name="BempegaldesleukinMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_DevelopmentDerivativeLiabilityTextBlock" abstract="false" name="DevelopmentDerivativeLiabilityTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="nktr_NonCashInterestExpenseRelatedToSaleOfRoyalties" abstract="false" name="NonCashInterestExpenseRelatedToSaleOfRoyalties" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_LiabilityRelatedToSaleOfFutureRoyaltiesTable" abstract="true" name="LiabilityRelatedToSaleOfFutureRoyaltiesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="nktr_PaymentMadeForMilestoneNotAchievedYearTwo" abstract="false" name="PaymentMadeForMilestoneNotAchievedYearTwo" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_SubleasesIncomeToBeReceived" abstract="false" name="SubleasesIncomeToBeReceived" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_RoyaltiesLiabilityMeasurementInput" abstract="false" name="RoyaltiesLiabilityMeasurementInput" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:decimalItemType"/>
  <xs:element id="nktr_UCBPharmaMember" abstract="true" name="UCBPharmaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_SaleOfStockValueAuthorizedInTransaction" abstract="false" name="SaleOfStockValueAuthorizedInTransaction" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_NumberOfOperatingBusinessSegment" abstract="false" name="NumberOfOperatingBusinessSegment" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nktr_BaxaltaIncorporatedOrTakedaPLCMember" abstract="true" name="BaxaltaIncorporatedOrTakedaPLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_ShareBasedPaymentArrangementOptionRSUsAndPSUsMember" abstract="true" name="ShareBasedPaymentArrangementOptionRSUsAndPSUsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrentNetOfIssuanceCosts" abstract="false" name="LiabilityRelatedToSaleOfPotentialFutureRoyaltiesNonCurrentNetOfIssuanceCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_LicenseAndCollaborationAgreementsTable" abstract="true" name="LicenseAndCollaborationAgreementsTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="nktr_PercentageOfDevelopmentMilestonesPaymentsToBeReceivedUnderCertainConditions" abstract="false" name="PercentageOfDevelopmentMilestonesPaymentsToBeReceivedUnderCertainConditions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nktr_ShareBasedCompensationPlansShareLimitForEveryOneShare" abstract="false" name="ShareBasedCompensationPlansShareLimitForEveryOneShare" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="nktr_ChangeInControlSeverancePaymentPeriodForExecutives" abstract="false" name="ChangeInControlSeverancePaymentPeriodForExecutives" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nktr_BMSCollaborationAgreementMember" abstract="true" name="BMSCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_InventoryAndSignificantSupplierConcentrationsPolicyTextBlock" abstract="false" name="InventoryAndSignificantSupplierConcentrationsPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="nktr_AstraZenecaAbMember" abstract="true" name="AstraZenecaAbMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_CashAndInvestmentsInMarketableSecuritiesLineItems" abstract="true" name="CashAndInvestmentsInMarketableSecuritiesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_OperatingLeaseMeasurementInput" abstract="false" name="OperatingLeaseMeasurementInput" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nktr_AuditorInformationAbstract" abstract="true" name="AuditorInformationAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_PercentageOfDevelopmentMilestonesPaymentsToBeReceivedIfConditionsOccur" abstract="false" name="PercentageOfDevelopmentMilestonesPaymentsToBeReceivedIfConditionsOccur" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nktr_ComputerFurnitureAndOtherMember" abstract="true" name="ComputerFurnitureAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_PercentageOfFundingPhaseThreeDevelopmentCostsOnAnIndicationByIndicationBasisBorne" abstract="false" name="PercentageOfFundingPhaseThreeDevelopmentCostsOnAnIndicationByIndicationBasisBorne" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nktr_MilestoneDomain" abstract="true" name="MilestoneDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_PaymentOfTransactionRelatedToPurchaseAndSaleAgreementIfThresholdIsAchieved" abstract="false" name="PaymentOfTransactionRelatedToPurchaseAndSaleAgreementIfThresholdIsAchieved" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_ThirdStFacilityMember" abstract="true" name="ThirdStFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_ScheduleOfLiabilityRelatedToSaleOfPotentialFutureRoyaltiesTableTextBlock" abstract="false" name="ScheduleOfLiabilityRelatedToSaleOfPotentialFutureRoyaltiesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="nktr_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockPlanOfferingPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardStockPlanOfferingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nktr_LiabilityRelatedToSaleOfPotentialFutureRoyaltiesTextBlock" abstract="false" name="LiabilityRelatedToSaleOfPotentialFutureRoyaltiesTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="nktr_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" abstract="true" name="OrganizationAndSummaryOfSignificantAccountingPoliciesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="nktr_MilestoneAxis" abstract="true" name="MilestoneAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="nktr_AreaOfLeasedSpace" abstract="false" name="AreaOfLeasedSpace" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:areaItemType"/>
  <xs:element id="nktr_SFJPharmaceuticalsMember" abstract="true" name="SFJPharmaceuticalsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" abstract="false" name="NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyalties" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_ManufacturingLaboratoryAndOtherEquipmentMember" abstract="true" name="ManufacturingLaboratoryAndOtherEquipmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_StockOptionsRSUsAndPSUsMember" abstract="true" name="StockOptionsRSUsAndPSUsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_DepreciablePropertyPlantAndEquipmentGross" abstract="false" name="DepreciablePropertyPlantAndEquipmentGross" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_OtherPartnerMember" abstract="true" name="OtherPartnerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_LiabilityRelatedToSaleOfFutureRoyaltiesRollForward" abstract="true" name="LiabilityRelatedToSaleOfFutureRoyaltiesRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_LeasesLineItems" abstract="true" name="LeasesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_IncreaseDecreaseInOperatingLeaseRightOfUseAssetsNetOfOperatingLeaseLiabilities" abstract="false" name="IncreaseDecreaseInOperatingLeaseRightOfUseAssetsNetOfOperatingLeaseLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_IncomeTaxesDisclosureLineItems" abstract="true" name="IncomeTaxesDisclosureLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nktr_RestructuringImpairmentAndOtherCostsOfTerminatedProgramMember" abstract="true" name="RestructuringImpairmentAndOtherCostsOfTerminatedProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_PaymentMadeForMilestoneNotAchievedYearOne" abstract="false" name="PaymentMadeForMilestoneNotAchievedYearOne" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_SaleOfStockConsiderationReceived" abstract="false" name="SaleOfStockConsiderationReceived" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyaltiesMember" abstract="true" name="NonCashRoyaltyRevenueRelatedToSaleOfFutureRoyaltiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_PaymentOfTransactionRelatedToPurchaseAndSaleAgreementIfThresholdIsNotAchieved" abstract="false" name="PaymentOfTransactionRelatedToPurchaseAndSaleAgreementIfThresholdIsNotAchieved" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nktr_BuildingAndLeaseholdImprovementsMember" abstract="true" name="BuildingAndLeaseholdImprovementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nktr_NKTR181Member" abstract="true" name="NKTR181Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
