Chiron Announces Effectiveness of Registration Statement for Resale of 1 5/8% Convertible Debentures Due 2033

Chiron Announces Effectiveness of Registration Statement for Resale of 1 5/8%
Convertible Debentures Due 2033 


EMERYVILLE, Calif., Jan. 9  /PRNewswire-FirstCall/ -- Chiron Corporation  today
announced that the Securities and Exchange Commission has declared effective its
registration statement on Form S-3 relating to the resale of $500 million
principal amount of its 1 5/8% Convertible Debentures due 2033 and the shares of
its common stock issuable upon conversion of the debentures.  The debentures
were originally issued in a private placement in July 2003.  Chiron will not
receive any proceeds from any resale by the selling security holders of the
debentures or the shares of common stock issuable upon conversion of the
debentures.

This press release does not constitute an offer to sell or the solicitation of
an offer to buy securities nor shall there be any sale of these securities in
any state in which such offer, solicitation or sale would be unlawful prior to
registration or qualification under the securities laws of any such state.  Any
offers of the securities will be made only by means of a prospectus.

About Chiron

Chiron Corporation, headquartered in Emeryville, California, is a global
pharmaceutical company that leverages a diverse business model to develop and
commercialize high-value products that make a difference in people's lives. The
company has a strategic focus on cancer and infectious disease.  Chiron applies
its advanced understanding of the biology of cancer and infectious disease to
develop products from its platforms in proteins, small molecules and vaccines. 
The company commercializes its products through three business units: 
biopharmaceuticals, vaccines and blood testing.  For more information about
Chiron, visit the company's website at http://www.chiron.com/.

This news release contains forward-looking statements that involve risks and
uncertainties and are subject to change.  A full discussion of the company's
operations and financial condition, including factors that may affect its
business and future prospects, is contained in documents the company has filed
with the SEC, including the form 10-Q for the quarter ended September 30, 2003,
and the form 10-K for the year ended December 31, 2002, and will be contained in
all subsequent periodic filings made with the SEC. These documents identify
important factors that could cause the company's actual performance to differ
from current expectations, including the outcome of clinical trials, regulatory
review and approvals, manufacturing capabilities, intellectual property
protections and defenses, stock-price and interest-rate volatility, and
marketing effectiveness.

Consistent with SEC Regulation FD, we do not undertake an obligation to update
the forward-looking information we are giving today. 

DATASOURCE: Chiron Corporation



CONTACT:  Corporate Communications, [phone], or Investor

Relations, [phone], both for Chiron



Web site:  http://www.chiron.com/ 

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