Extensive planning and preparation by public health agencies were required for the provision of public health services during the 1996 Centennial Olympic Games, which brought together more than 10000 athletes from 197 countries and more than 2 million visitors. Public health activities included the development and use of an augmented surveillance system to monitor health conditions and detect disease outbreaks; creation and implementation of 6 environmental health regulations; establishment of a central Public Health Command Center and response teams to coordinate response to public health emergencies; planning for potential mass casualties and the provision of emergency medical services; implementation of strategies for the prevention of heat-related illness; and distribution of health promotion and disease prevention information. Public health agencies should take the lead in organizing and implementing a system for preventing and managing public health issues at future large-scale public events such as the Olympics.