<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2003-08-01</periodOfReport>


    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001009759</issuerCik>
        <issuerName>CAPSTONE TURBINE CORP</issuerName>
        <issuerTradingSymbol>cpst</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001257778</rptOwnerCik>
            <rptOwnerName>BOSCO CARMINE F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>21211 NORDHOFF STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHATSWORTH</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>91311</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>



    <ownerSignature>
        <signatureName>By Susan N. Cayley, Attorney in Fact, Power of Attorney for Carmine F. Bosco</signatureName>
        <signatureDate>2003-08-04</signatureDate>
    </ownerSignature>

</ownershipDocument>

