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

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2007-05-08</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001170593</issuerCik>
        <issuerName>PRIMUS GUARANTY LTD</issuerName>
        <issuerTradingSymbol>PRS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001189239</rptOwnerCik>
            <rptOwnerName>LUCK FIONA E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>XL HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>ONE BERMUDIANA ROAD</rptOwnerStreet2>
            <rptOwnerCity>HAMILTON</rptOwnerCity>
            <rptOwnerState>D0</rptOwnerState>
            <rptOwnerZipCode>HM 11</rptOwnerZipCode>
            <rptOwnerStateDescription>BERMUDA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <remarks>No securities are beneficially owned.</remarks>

    <ownerSignature>
        <signatureName>/s/ Fiona E. Luck</signatureName>
        <signatureDate>2007-05-16</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Howard Yaruss by power of attorney</signatureName>
        <signatureDate>2007-05-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
