X0201 4/A2003-06-092003-06-10 0000706539 CHIRON CORP CHIR 0001233539 PATTERSON LEONE D 4560 HORTON STREET EMERYVILLE CA 94608 0100ControllerCommon Stock2003-06-094M0200021.4688A6554DCommon Stock2003-06-094S0100045.07D5554DCommon Stock2003-06-094S0100045.08D4554DEmployee Stock Option (Right to Buy)21.46882003-06-094M0200021.4688D2000-02-262009-02-26Common Stock20002687DEmployee stock option granted under the Chiron 1991 Stock Option Plan in transaction exempt under Rule 16b-3.The number of shares previously reported under column 5 of Table I of the Reporting Person's Form 4 for the transaction date of June 9, 2003 contained a typographical error; the amount of securities beneficially owned following reported transaction(s) as of that date was 4,554.Leone D. Patterson by Carolyn Mar-Andreotti as Atty-in-Fact2003-10-24