<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2011-06-06</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000859475</issuerCik>
        <issuerName>TRIDENT MICROSYSTEMS INC</issuerName>
        <issuerTradingSymbol>TRID</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001264046</rptOwnerCik>
            <rptOwnerName>BASTANI BAMI</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TRIDENT MICROSYSTEMS</rptOwnerStreet1>
            <rptOwnerStreet2>1170 KIFER ROAD</rptOwnerStreet2>
            <rptOwnerCity>SUNNYVALE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94086</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO, PRESIDENT</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <ownerSignature>
        <signatureName>By: David L. Teichmann, Attorney-in-Fact  For: Bami Bastani</signatureName>
        <signatureDate>2011-06-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
