In a consecutive series of 132 motorcycle and moped riders killed in 1977-1983 in southern Sweden and examined post mortem, almost half of the fatal injuries of the head and neck occurred remote from the point of impact, namely certain intracranial injuries without fractures, ring fractures of the base of the skull, disruption of the junction of the head and neck and injuries of the cervical spine. Ring fractures of the base of the skull were noticeably more frequent in motorcyclists than in car occupants who died. Injuries occurring remote from the point of impact were often the result of impacts against the anterior part of the head, especially against the face. All 5 riders suffering disruption of the junction of the head and neck were helmeted, which suggests that the helmet may promote such injuries. In some of these cases, no sign of impact against the head could be detected. The inertia of the head, enhanced by the helmet, is supposed to contribute to some of these injuries, which calls into question the protection provided by the helmet. Fatal head injuries at the point of impact were mostly found on the lateral-posterior part of the head. These injuries were often irrespective of whether or not a helmet was used. The points of impact were found mainly rung around the head. Protective helmets should be improved in order to give better protection against injuries at the site of impact, especially in the above-mentioned area, to give better protection of the face and to increase energy-absorbing capacity.(ABSTRACT TRUNCATED AT 250 WORDS)