During the past two years we studied six infants with subdural collections of fluid. All patients had macrocrania and excessive transillumination of the head. Rapid head growth was common but five patients were otherwise asymptomatic. Subdural taps performed on five children confirmed the presence of abnormal fluid over the cerebral convexities. Subdural fluid in four patients was compatible with effusion and in another with a hematoma. Computerized tomographic evaluation of all infants showed ventricular enlargement, wide cerebral sulci, decreased density in the anterior temporal regions, large sylvian cisterns, prominent interhemispheric fissures, and decreased density over the cerebral convexities. The CT findings resembled cerebral atrophy but psychomotor development and neurologic examinations have been norma.