<SUBMISSION>
<ACCESSION-NUMBER>0001209191-06-051196
<TYPE>3/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20060921
<FILING-DATE>20060921
<DATE-OF-FILING-DATE-CHANGE>20060921
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>COMMVAULT SYSTEMS INC
<CIK>0001169561
<ASSIGNED-SIC>7372
<IRS-NUMBER>000000000
<STATE-OF-INCORPORATION>DE
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>2 CRESCENT PLACE
<CITY>OCEANPORT
<STATE>NJ
<ZIP>07757-0900
<PHONE>7328704000
</BUSINESS-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>CREDIT SUISSE/
<CIK>0000824468
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3/A
<ACT>34
<FILE-NUMBER>001-33026
<FILM-NUMBER>061103158
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>PO BOX 900
<STREET2>FHLS
<CITY>ZURICH
<STATE>V8
<ZIP>CH 8070
<PHONE>41 1 212 16 16
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>PO BOX 900
<CITY>ZURICH
<STATE>V8
<ZIP>CH 8070
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>CREDIT SUISSE FIRST BOSTON/
<DATE-CHANGED>19970211
</FORMER-NAME>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>CREDIT SUISSE
<DATE-CHANGED>19921119
</FORMER-NAME>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>3/A
<SEQUENCE>1
<FILENAME>bny25266_csa1.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2006-09-21</periodOfReport>

    <dateOfOriginalSubmission>2006-09-21</dateOfOriginalSubmission>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001169561</issuerCik>
        <issuerName>COMMVAULT SYSTEMS INC</issuerName>
        <issuerTradingSymbol>CVLT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000824468</rptOwnerCik>
            <rptOwnerName>CREDIT SUISSE/</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>11 MADISON AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10010</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <remarks>This Form 3/A is filed to amend and withdraw in its entirety the Form 3 filed by Credit Suisse (on behalf of the Investment Banking
Division) on September 21, 2006.</remarks>

    <ownerSignature>
        <signatureName>/s/ Ivy Dodes for Credit Suisse, on behalf of the Investment Banking Division</signatureName>
        <signatureDate>2006-09-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
