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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,
 OO4GG2/I/uHMCrhO0yo5qnwEJXCxtGyetvnsfPLAg+lFc/YVsddFMa3gtLwQ5iwu
 ByII6Iahaw9FLGSl/NydyA==

<SEC-DOCUMENT>0001233539-04-000001.txt : 20040102
<SEC-HEADER>0001233539-04-000001.hdr.sgml : 20040101
<ACCEPTANCE-DATETIME>20040102155514
ACCESSION NUMBER:		0001233539-04-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031231
FILED AS OF DATE:		20040102

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PATTERSON LEONE D
		CENTRAL INDEX KEY:			0001233539

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12798
		FILM NUMBER:		04501341

	BUSINESS ADDRESS:	
		STREET 1:		CHIRON CORP.
		STREET 2:		4560 HORTON STREET
		CITY:			EMERYVILLE
		STATE:			CA
		ZIP:			94608

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CHIRON CORP
		CENTRAL INDEX KEY:			0000706539
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				942754624
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		4560 HORTON ST
		CITY:			EMERYVILLE
		STATE:			CA
		ZIP:			94608
		BUSINESS PHONE:		5106558730
</SEC-HEADER>
<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>2003-12-31</periodOfReport>
    <issuer>
        <issuerCik>0000706539</issuerCik>
        <issuerName>CHIRON CORP</issuerName>
        <issuerTradingSymbol>CHIR</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001233539</rptOwnerCik>
            <rptOwnerName>PATTERSON LEONE D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4560 HORTON STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EMERYVILLE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94608</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Controller</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-31</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>F</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>108</value></transactionShares><transactionPricePerShare><value>56.66</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4364</value><footnoteId id="F1"/><footnoteId id="F2"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIn
directOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><footnotes><footnote id="F1">This total includes 1,100 share rights awarded pursuant to the Chiron 1991 Stock Option Plan in transaction exempt under Rule 16b-3, which share rights are subject to certain vesting.</footnote><footnote id="F2">The amount of securities beneficially owned includes Reporting Person's purchase of 176 shares under Issuer's Employee Stock Purchase Plan, which purchase was not reportable under Section 16(a) of the Securities Exchange Act of 1934, as amended.</footnote></footnotes><remarks/><ownerSignature><signatureName>Leone D. Patterson by Naima Robinson as Atty-in-Fact</signatureName><signatureDate>2004-01-02</signatureDate></ownerSignature></ownershipDocument>

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