Planning for environmental health management of the Athens 2004 Olympic Games included assessment of the capacity and deficiencies of relevant public health agencies in Athens and the other four Olympic cities with 17 detailed questionnaires. Different estimates of the expected number of visitors were made on the basis of experience from previous Olympic Games. Potential public health risks were identified and prioritized. A number of deficiencies in personnel, resources, training, and coordination were identified in most agencies. One hundred and ninety-six environmental health inspectors were expected to work during the Olympic period. Around 18,000 athletes and escorts from 201 countries were expected to participate in the Olympic Games and 7,000 to participate in the Para-Olympic Games. Three different scenarios regarding the number of expected visitors were explored; the most probable estimate being 1,950,000 visitors. Foodborne diseases, waterborne diseases, and heat-related illnesses were considered of high priority during the Olympic period, as were traffic accidents. The Olympic Games are a difficult assignment that demands extensive planning, appropriate resources, and timely reporting and coordination among the various public health agencies.