Chiron Response to ValueAct Letter

Chiron Corporation (NASDAQ:CHIR) today issued the
following statement in response to a letter received today from
ValueAct Capital:
   We continue to believe that ValueAct should want to meet with
Chiron's independent directors and management team to fully understand
the serious challenges facing the Company and to gain a realistic
perspective on our future prospects. Our independent directors and
management team continue to strongly recommend the Novartis
transaction and believe that it represents a full and fair price and
is a superior alternative for Chiron's public stockholders to Chiron
remaining a standalone company.

   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.