Medical services planning for the 1996 Summer Olympics in Atlanta began in 1991. Because of the city's climate, heat-related illnesses were thought to pose substantial risk. Injuries were expected to produce a major proportion of medical visits. Outbreaks of infectious diseases were possible. Planners also considered the possibility of a chemical or biological terrorist attack. Eight million spectator tickets were sold, which was double the number sold for the 1984 Olympics in Los Angeles. From July 6 through August 4, Atlanta's Olympics Medical Services Department provided care for 44,142 people, or 22.9 visits per 10,000 in attendance. These rates were comparable to Los Angeles' 16 per 10,000 in attendance. At its peak, the medical services department in Atlanta treated an average of 537 patients a day. A physician examined 10,715 people, most of whom were spectators (3,482), followed by volunteers (3,280), athletes (1,804) and other groups. For specific diagnoses, a sprain or strain was the most common reason for a visit (1,450), followed by upper respiratory tract infection (922), heat cramps/dehydration (801), contusion/abrasion (777), other injury (520), laceration (487), and nausea/vomiting (387). Injuries were the most common reason for athletes' visits (51.9 percent). Heat-related illnesses were the most common reason for spectators' visits (21.6 percent). There were 3,346 medical care volunteers, including 664 physicians, 474 nurses, 246 paramedics, 242 emergency medical technicians, 411 American Red Cross first responders, 796 trainers, 30 dentists, and 30 podiatrists. A 2,250-square-meter polyclinic was open 24 hours a day and provided care for the athletes, including orthopedics, ophthalmology and gynecology. Eight-four spectator care stations operated at 24 competition venues, providing care ranging from dealing with cardiac arrest to minor medical problems. Mobile aid teams circulated among spectators. The cost of providing medical care was $4.36 million. No tax dollars were used. Tables, references