Chiron Announces Termination of SEC Investigation

Chiron Corporation (Nasdaq:CHIR) today announced that
the staff of the Securities and Exchange Commission (SEC) has decided
to terminate its investigation of whether Chiron violated any federal
securities laws in connection with the previous suspension by the UK
Medicines and Healthcare products Regulatory Agency (MHRA) of Chiron's
license to manufacture FLUVIRIN(R) influenza virus vaccine and has
ended its inquiry into the company's restatement of financial results
for the second and third quarters of 2004. Chiron has been informed
that no enforcement action has been recommended against the company in
connection with these matters.

   About Chiron

   Chiron delivers innovative and valuable products to protect human
health by advancing pioneering science across the landscape of
biotechnology. The company works to deliver on the limitless promise
of science and make a positive difference in people's lives. For more
information about Chiron, please visit www.chiron.com.