UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934

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Definitive Proxy Statement

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Soliciting Material Pursuant to §240.14a-12

CHIRON CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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Chiron Corporation

4560 Horton Street

Emeryville, California 94608-2916

510.655.8730

Fax 510.655.9910

News Release

Contacts:

Chiron Corporate Communications &

Investor Relations

Media:

(510) 923-6500

Investors:

(510) 923-2300