To determine whether the presence of a physician in the prehospital setting influences patient outcome, the predicted mortality of 258 patients with blunt trauma treated and transported by a medical helicopter staffed by a flight nurse and flight paramedic was compared with that of 316 similar patients with blunt trauma treated and transported by a medical helicopter staffed by a flight nurse and flight physician. All patients were randomized between the two treatment teams. The mortality of the patients treated by the flight nurse/flight paramedic team was that predicted by the methodology. The mortality of the patients treated by the flight nurse/flight physician team was 35% lower than that predicted, and significantly lower than that of the flight nurse/flight paramedic-staffed helicopter.