A prospective study was carried out of 784 adults (aged 13 years and over) with recent head injuries who attended the Accident and Emergency Department of the Glasgow Royal Infirmary during an 11-week period (April-June 1978). One-third were caused by assault and only one-tenth by road traffic accidents. Half the patients had recently ingested alcohol, one-quarter of all patients had at least a brief period of post-traumatic amnesia (PTA). The overall admission rate was 28 per cent. Radiography of the skull was performed in 65 per cent and a fracture seen in 5 per cent of these. One-quarter of the patients had at least one unsatisfactory radiograph. Two patients whose fractures were initially missed on radiography were not admitted. Seven of the 24 patients with fractures had no clinical evidence of brain damage (no PTA, no impaired conscious level, no focal neurological signs or symptoms), but all had wounds of the scalp. One-third of all patients did not have radiography of the skull performed, nor were they admitted to hospital, yet one-quarter of these had some evidence of brain damage.