<SUBMISSION>
<ACCESSION-NUMBER>0001179110-04-000045
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20031230
<FILING-DATE>20040102
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>HARRIS J MILTON
<CIK>0001236923
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-24006
<FILM-NUMBER>04501283
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O NEKTAR THERAPEUTIC
<STREET2>150 INDUSTRIAL ROAD
<CITY>SAN CARLOS
<STATE>CA
<ZIP>94070
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>NEKTAR THERAPEUTICS
<CIK>0000906709
<ASSIGNED-SIC>2834
<IRS-NUMBER>943134940
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>150 INDUSTRIAL RD
<CITY>SAN CARLOS
<STATE>CA
<ZIP>94070
<PHONE>6506313100
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>150 INDUSTRIAL ROAD
<CITY>SAN CARLOS
<STATE>CA
<ZIP>94070
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>INHALE THERAPEUTIC SYSTEMS INC
<DATE-CHANGED>19980723
</FORMER-COMPANY>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>INHALE THERAPEUTIC SYSTEMS
<DATE-CHANGED>19940303
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-12-30</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000906709</issuerCik>
        <issuerName>NEKTAR THERAPEUTICS</issuerName>
        <issuerTradingSymbol>NKTR</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001236923</rptOwnerCik>
            <rptOwnerName>HARRIS J MILTON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>150 INDUSTRIAL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN CARLOS</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94070</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>President of Nektar AL</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-12-30</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>50000</value>
</transactionShares>
<transactionPricePerShare><value>14.10</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>1130598</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-12-30</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
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<equitySwapInvolved>0</equitySwapInvolved>
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<transactionAmounts><transactionShares><value>50000</value>
</transactionShares>
<transactionPricePerShare><value>14.10</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>1177011</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>By Puffinus, L.P.</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
</nonDerivativeTable>
<derivativeTable></derivativeTable>
<footnotes></footnotes>
<ownerSignature><signatureName>/s/ Paula S. Kasler</signatureName>
<signatureDate>2004-01-02</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
