<SUBMISSION>
<ACCESSION-NUMBER>0000920371-03-000066
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20031211
<FILING-DATE>20031212
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LOURAS PETER N
<CIK>0001087158
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-13429
<FILM-NUMBER>031052787
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>4120 DUBLIN BOULEVARD
<STREET2>SUITE 400
<CITY>DUBLIN
<STATE>CA
<ZIP>94568
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>4120 DUBLIN BOULEVARD
<STREET2>SUITE 400
<CITY>DUBLIN
<STATE>CA
<ZIP>94568
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>SIMPSON MANUFACTURING CO INC /CA/
<CIK>0000920371
<ASSIGNED-SIC>3420
<IRS-NUMBER>943196943
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>4120 DUBLILN BLVD STE 400
<CITY>DUBLIN
<STATE>CA
<ZIP>94568
<PHONE>9255609000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>4120 DUBLIN BLVD STE 400
<CITY>DUBLIN
<STATE>CA
<ZIP>94568
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-12-11</periodOfReport>
    <issuer>
        <issuerCik>0000920371</issuerCik>
        <issuerName>SIMPSON MANUFACTURING CO INC /CA/</issuerName>
        <issuerTradingSymbol>NYSE:SSD</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001087158</rptOwnerCik>
            <rptOwnerName>LOURAS PETER N</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4120 DUBLIN BLVD., SUITE 400</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DUBLIN</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94568</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
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