Abstract Five hundred and thirty-eight motorcyclist (MCs) and 523 pedal cyclist (PCs) victims of road traffic accidents were studied. Nineteen out of 21 of the PCs who died suffered major head injuries (AIS⩾4) whereas 21 out of 87 MCs suffered no head injury at all. PCs who died more commonly sustained a head injury, and on average sustained more severe head injuries than dying MCs. Surviving PCs suffered head injuries more commonly than surviving MCs. MCs who died having sustained a head injury usually suffered other, often multiple, injuries of equal or greater severity whereas dying PCs commonly suffered no other injury of comparable severity to their head injury. It is suggested that if the severity of head injuries sustained by injured PCs could be reduced (e.g. by wearing helmets) survival rates would improve as most fatalities do not involve other major injuries. Helmets might also reduce the incidence and severity of head injuries in PCs who survive their accident.