<SUBMISSION>
<ACCESSION-NUMBER>0001179110-04-022623
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20040304
<FILING-DATE>20041207
<DATE-OF-FILING-DATE-CHANGE>20041207
<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>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>CHESS ROBERT
<CIK>0001227886
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>000-24006
<FILM-NUMBER>041188218
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O PHARSIGHT
<STREET2>8OO WEST EL CAMINO REAL STE 200
<CITY>MOUNTAIN VIEW
<STATE>CA
<ZIP>94040
<PHONE>6503143817
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2004-03-04</periodOfReport>

    <dateOfOriginalSubmission>2004-03-08</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000906709</issuerCik>
        <issuerName>NEKTAR THERAPEUTICS</issuerName>
        <issuerTradingSymbol>NKTR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001227886</rptOwnerCik>
            <rptOwnerName>CHESS ROBERT</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>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Chairman</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-03-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16666</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>300367</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares of Common Stock are issued upon the vesting of restricted stock units granted to the holder.  1/6th of the restricted stock units shall vest on December 31, 2004; an additional 1/3rd of the restricted units shall vest on December 31, 2005 and the balance of the restricted stock units shall vest on December 31, 2006.  The restricted stock units will be fully vested on December 31, 2006.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Paula S. Kasler</signatureName>
        <signatureDate>2004-12-07</signatureDate>
    </ownerSignature>
</ownershipDocument>

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