We investigated the incidence of fatal traffic accidents caused by sudden incapacity of the driver due to cardiac and other illnesses. The retrospective analysis was gleaned from Finnish traffic accident data files from 1984-1989, and police records of traffic accidents, from Canton de Vaud, Switzerland from 1986-1989. The annual rates of all traffic fatalities per million inhabitants were 125 in Finland and 212 in Vaud. Sudden driver incapacity due to acute illness caused 1.8 and 7.3 automobile driver deaths annually per million inhabitants in Finland and in Vaud, respectively. The corresponding rates for all-cause traffic deaths were 326 and 423, for driver deaths 105 and 167, and for those due to driver incapacity 4.7 and 15.6. Sudden driver incapacity caused 1.5% of all traffic deaths in Finland, and 3.4% in Vaud. Probable cardiac arrest caused 2.1% of all drivers' deaths in Finland and 1.7% in Vaud, respectively. Deaths caused by professional drivers' sudden incapacity were responsible for 0.11% of all traffic deaths in Finland, and for 0% in Vaud. Old age and short mileage were associated with illness-caused accidents. Accidents caused by sudden incapacity of the driver are rare causes of traffic deaths and hard to foresee. While this report relates to all drivers, we suggest there should be individual risk stratification for professional drivers with heart disease. However, non-professional drivers who are elderly and who have symptomatic cardiac disease should limit their driving to short distances and at low speed.