Classical migraine, including incapacitating visual field defects, repeatedly developed in five young men immediately after blows to the head while playing football and in no other circumstances. A similar condition occurred in a professional boxer and an isolated attack in a boy footballer. Prophylactic treatment with ergotamine tartrate may not be wholly successful and it may be necessary to give up the sport. Any unitary theory of causation of attacks of migraine must account for prodromal symptoms immediately after head injury.