We have conducted a three-year prospective study of medical incidents on a commercial airline. A telemedicine service was available via an on-board satellite phone. During the study period there were 3364 medical incidents. The most common incident was collapse (n = 2310, 57%). Telemedicine was used in 323 of the cases (9%). Neurological patients, mostly stroke and seizures, excluding psychiatric diseases, were seen in 27% of the telemedicine cases (n = 83). Most of the cases involved middle-aged people, not the elderly. The group of patients that needed diversion (n = 27) was compared to the cases staying on board (n = 275). None of the patients in the non-diversion group deteriorated. All unstable patients forced a diversion. Doctors on board used the service in more severe cases, whereas laymen used the service in less severe cases. The results of the present study demonstrate the advantage of using simple teleconsultation in cases of medical emergency on board an aircraft.