We performed a one-year prospective survey of emergency medical responses to travelers at an international airport to observe the frequency and type of emergencies experienced in flight and before and after travel. Emergency personnel evaluated a total of 1107 people; 754 (68%) were travelers, 232 (21%) were employees of the airport or airlines, and 118 (11%) were area residents. Of the 754 travelers, 190 (25%) experienced their problem during flight; the aircraft made an unscheduled landing for seven of these travelers. The frequency of in-flight emergencies was 1 per 753 inbound flights, or 1 per 39,600 inbound passengers. The most common emergency problems among all travelers were abdominal pain, chest pain, shortness of breath, syncope, and seizures; 25% of the emergencies were caused by minor trauma. The majority of emergencies among air travelers (75% [564/754]) happened on the ground within the air terminal. Most problems (84% [633/754]) were effectively handled by personnel trained as emergency medical technicians. The types of problems encountered suggest that the "doctors only" medical kit now required aboard US air carriers contains clinically useful items and should continue to be required on board.