We analyzed the records of 4,169 victims of traffic collisions fatally injured during the period 1972 to 1985. Chest injuries were recorded as the main cause of death in 1,121 victims; 207 of them had worn a seatbelt. Rupture of the heart was found at autopsy in 75 of these seatbelt wearers. Exact information on the location and the size of the heart rupture was available in 47 cases. For a control group, we analyzed 47 randomly chosen unbelted victims who had sustained a fatal heart rupture in comparable collisions. The site of cardiac injury was a ventricle in 75.5%. In frontal impact collisions the mechanism leading to heart rupture is usually crushing against the steering wheel, even in seatbelt wearers. Most of the victims had multiple injuries, and only serious collisions, often with a heavier vehicle, led to fatal heart rupture.