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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Afk+8BSBnaH+BSB8ZBxeGV6ADYyOrb81r2EQs+oLrPDeKhP//lQleFAIbCmtm1OJ
 TafcFmv5EgwE0lkRtex8RQ==

<SEC-DOCUMENT>0001246151-04-000015.txt : 20040114
<SEC-HEADER>0001246151-04-000015.hdr.sgml : 20040114
<ACCEPTANCE-DATETIME>20040114201424
ACCESSION NUMBER:		0001246151-04-000015
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:			CHOU CARLOS
		CENTRAL INDEX KEY:			0001275827

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20725
		FILM NUMBER:		04526039

	BUSINESS ADDRESS:	
		STREET 1:		15 ARDMORE PARK
		STREET 2:		#09-03
		CITY:			SINGAPORE
		STATE:			U0
		ZIP:			259959
		BUSINESS PHONE:		01181354647800

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>c0001275827d20040114f3f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>3</documentType><periodOfReport>2004-01-05</periodOfReport><noSecuritiesOwned>0</noSecuritiesOwned><issuer><issuerCik>0001006835</issuerCik><issuerName>SIEBEL SYSTEMS INC</issuerName>        <issuerTradingSymbol>SEBL</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001275827</rptOwnerCik><rptOwnerName>CHOU CARLOS</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>C/O SIEBEL SYSTEMS SINGAPORE</rptOwnerStreet1><rptOwnerStreet2>3 ANSON ROAD # 17-01, SPRINGLEAF TOWER</rptOwnerStreet2><rptOwnerCity>SINGAPORE</rptOwnerCity><rptOwnerState></rptOwnerState><rptOwnerZipCode>079909</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>President, Asia Pacific Sales</officerTitle><otherText></otherText></report
ingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4568</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>8.66</value></conversionOrExercisePrice><exerciseDate><value>2004-05-01</value><footnoteId id="F1"/></exerciseDate><expirationDate><value>2009-04-30</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>10000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwn
ership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>14.28</value></conversionOrExercisePrice><exerciseDate><value>2004-12-29</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2009-12-28</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>60000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>16.69</value></conversionOrExercisePrice><exerciseDate><value>2000-10-04</value>
<footnoteId id="F3"/></exerciseDate><expirationDate><value>2009-10-03</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>100000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>17.7</value></conversionOrExercisePrice><exerciseDate><value>2002-10-24</value><footnoteId id="F4"/></exerciseDate><expirationDate><value>2011-10-23</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>28500</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></di
rectOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>23.88</value></conversionOrExercisePrice><exerciseDate><value>2002-04-05</value><footnoteId id="F5"/></exerciseDate><expirationDate><value>2011-04-04</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>44000</value></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><footnotes><footnote id="F1">Option becomes exercisable at a rate of 20% on May 1, 2004 and 5% for each quarter of service thereafter.</footnote><footnote id="F2">Option becomes exercisable at a rate of 20% on Decemb
er 29, 2004 and 5% for each quarter of service thereafter.</footnote><footnote id="F3">Original option was for 200,000, of which 100,000 shares have been exercised.  Option becomes exercisable at a rate of 20% on October 4, 2000 and 5% for each quarter of service thereafter.</footnote><footnote id="F4">Original option was for 30,000 shares, of which 1,500 shares have been exercised.  The option becomes exercisable at a rate of 5% on January 24, 2002 and 5% for each quarter of service thereafter.</footnote><footnote id="F5">Option is fully vested.</footnote></footnotes><ownerSignature><signatureName>Carlos  Chou</signatureName><signatureDate>2004-01-14</signatureDate></ownerSignature></ownershipDocument>

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