The authors examined the patterns of injury and death rates of patients involved in vehicle-related accidents who were admitted to the Regional Trauma Unit of Sunnybrook Health Science Centre in Toronto. Information was collected prospectively over a 36-month period. The subjects were placed in one of three mechanism-of-injury categories: four-wheel passenger vehicles, motorcycles and pedestrians. The patterns of injury were classified as primarily to the craniofacial and neck area, the torso, the extremities or to multiple regions. There were 815 patients who were involved in vehicle-related crashes and who suffered moderate to severe injuries (at least one region scoring more than 3 on the abbreviated injury scale). The death rate was 13% overall but was 21% in the group receiving multiple injuries. By mechanism of injury the death rates were: pedestrian group 20%, motorcycle group 18% and passenger-vehicle group 11% (p less than 0.01, chi 2 analysis). There was no difference in the mean injury severity score among the mechanism of injury groups. A higher proportion of the passenger-vehicle group sustained isolated craniofacial and torso injuries, and the pedestrian and motorcycle groups sustained more extremity injuries (p less than 0.001, chi 2 analysis). The results reveal a clear association between mechanism of injury and the patterns of injury observed.