Chiron Announces May 27 Webcast of Annual Meeting of Stockholders

EMERYVILLE, Calif., May 20 /PRNewswire-FirstCall/ -- Chiron Corporation today announced that it will hold its Annual Meeting of Stockholders on Thursday, May 27, 2004, at 1:00 p.m. EDT. Investors may access a live audio webcast of the presentation at http://www.chiron.com/webcast . We recommend logging on 15 minutes early in order to register and download any necessary software.

About Chiron

Through its global Blood Testing, Vaccines and BioPharmaceuticals businesses, Chiron Corporation addresses human suffering with more than 50 diverse products to detect, prevent and treat disease worldwide. The company’s consistent success has come from its pioneering science, skill in delivering innovations in biotechnology and disciplined business approach. Chiron believes that science has the power to improve people’s lives and harnesses that power to transform public health.

This year, Chiron Vaccines celebrates 100 years of advancing medicine with the anniversary of two founding companies. In 1904, Emil von Behring and Achille Sclavo independently started companies in Germany and Italy, respectively, dedicated to the research, development and manufacture of vaccines to protect humanity from infectious disease. As the fifth-largest vaccine manufacturer in the world, Chiron remains dedicated to the legacies of von Behring and Sclavo to prevent disease and develop new vaccines to improve human health globally.

For more information about Chiron, visit the company’s website at http://www.chiron.com/.

Chiron Corporation

CONTACT: Corporate Communications, +1-510-923-6500, or InvestorRelations, +1-510-923-2300, both of Chiron Corporation