The management of 405 patients presenting with head injury to an accident and emergency department was assessed. Sixty-nine patients were admitted, although this number should have been 127 according to current guidelines on the management of head injury. Only three attenders were admitted inappropriately according to these guidelines. An accident and emergency observation ward was open on weekdays only; at weekends, patients with head injury were admitted to a general surgical ward. When the observation ward was open, 51 of the 76 patients (67 per cent) presenting with admission criteria were admitted. When closed, only 15 of the 51 patients (29 per cent) with these criteria were admitted. Guidelines were applied effectively to reduce the number of unnecessary admissions, but there was a significant number of patients with minor head injury who were discharged inappropriately. This number was much reduced when an observation ward was available.