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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 VI8NcGobQsp4rz5F1mNP4MJpz39w/vIPHmRtr8/glRrTQhr7sYK+FQaDH2GUpukE
 mxxJ14VidFu1V6LVMUUHqQ==

<SEC-DOCUMENT>0001246151-04-000011.txt : 20040114
<SEC-HEADER>0001246151-04-000011.hdr.sgml : 20040114
<ACCEPTANCE-DATETIME>20040114200741
ACCESSION NUMBER:		0001246151-04-000011
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040105
FILED AS OF DATE:		20040114

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			WESTON NEIL M
		CENTRAL INDEX KEY:			0001275829

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20725
		FILM NUMBER:		04526031

	BUSINESS ADDRESS:	
		STREET 1:		SIEBEL SYSTEMS INC
		STREET 2:		THE GLANTY, SIEBEL CENTRE
		CITY:			EGHAM, SURREY, ENGLAND
		STATE:			X0
		ZIP:			TW209DW
		BUSINESS PHONE:		011441784494826

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SIEBEL SYSTEMS INC
		CENTRAL INDEX KEY:			0001006835
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				943187233
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2207 BRIDGEPOINTE PARKWAY
		CITY:			SAN MATEO
		STATE:			CA
		ZIP:			94404
		BUSINESS PHONE:		6504775000

	MAIL ADDRESS:	
		STREET 1:		2207 BRIDGEPOINTE PARKWAY
		CITY:			SAN MATEO
		STATE:			CA
		ZIP:			94404
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2004-01-05</periodOfReport>


    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001006835</issuerCik>
        <issuerName>SIEBEL SYSTEMS INC</issuerName>
        <issuerTradingSymbol>SEBL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001275829</rptOwnerCik>
            <rptOwnerName>WESTON NEIL M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SIEBEL SYSTEMS UK, LTD.</rptOwnerStreet1>
            <rptOwnerStreet2>THE GLANTY, SIEBEL CENTRE</rptOwnerStreet2>
            <rptOwnerCity>EGHAM, SURREY</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>TW209DW</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, EMEA Sales</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>



    <ownerSignature>
        <signatureName>Neil M. Weston</signatureName>
        <signatureDate>2004-01-14</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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