This study was designed to examine trauma patterns in motor vehicle collisions among lap belted and lap/shoulder belted children. The sample was taken from a larger study of child occupants presenting to emergency rooms for evaluation and treatment of crash related injuries in a single county over a five year period, 1980-1985. Two hundred and twenty-nine cases were selected for analysis. Eighty-eight were in a lap/shoulder belt in the front seat; 141 were in a lap belt in the back seat. There were no significant differences in injury severity, anatomic site of injury or rate of hospitalization between those in a lap and those in a lap/shoulder belt. However, certain patterns and mechanisms of injuries were apparent. Injuries to the head/face were most common, and were sustained by nearly 50% of the entire sample. Ten percent of the lap/shoulder belted and 12% of the lap belted sustained abdominal injuries. Cervical strain injuries were sustained by 21% of the lap/shoulder belted and 14% of the lap belted. The most common mechanism of injury was impact with the vehicle interior. Injuries were also incurred from flexion/extension of the neck and from the seat belt system. While offering overall protection, patterns and mechanisms of injury were observed which raise some concern regarding use of these systems by children.