Objective: Analysis of a high-volume military air ambulance unit and review of the U.S. Army air medical transport system and Military Assistance to Safety and Traffic (MAST) program. Setting: A remote medical system with numerous ground emergency medical services. Inclusion: All patients transported between January 1, 1996, and February 28, 1998. Exclusion: Patients who were dead on the scene or for whom records were unavailable. Methods: Retrospective review of transport and available inpatient records. Results: A total of 517 patients were transported during the study period; 461 patients met the inclusion criteria (89%). Of these, 70% were classified as trauma patients, and 30% had medical or other surgical diagnoses. Prehospital responses accounted for 71.6% of transports, and 28.4% were interhospital transfers.