An analysis of 19 confirmed cases of subdural empyema treated in our unit during a 29-month period ending in May 1990 revealed that this was a disease of young males (mean age 19.6 yrs: male:female ratio 5:1) that was frequently associated with paranasal sinusitis. We have identified a characteristic symptom complex which when present together with focal neurological deficits makes the diagnosis highly probable. This consists of fever, headache, altered level of consciousness and frontal scalp swelling. In a practice setting where neuroradiological confirmation of the diagnosis is not always practicable, this clinical syndrome is helpful and should prompt early burr hole exploration of the subdural space. The only deaths (2 patients; 11%) occurred in patients who presented in coma. The remaining were either normal (6 patients) or continued to improve after treatment, which consisted of multiple burr hole drainage, broad spectrum antimicrobial treatment and eradication of the source of infection.