Seven cases of posterior fossa subdural empyema were treated between 1955 and 1984; 3 of the patients survived. The two sources of infection were otogenic and spread from supratentorial subdural empyema complicating acute frontal sinusitis. Investigations including computerized axial tomography (CT) scans were sometimes equivocal and diagnosis was sometimes delayed. Posterior fossa craniectomy appeared to be the operation of choice; all the patients treated only by posterior fossa burr holes died. Early aggressive surgical intervention in such cases should result in a minimal morbidity.