One hundred nine head-injured patients with epidural and acute and chronic subdural hematomas were evaluated by computed tomography (CT). Eighty-two patients had subsequent CT examinations in order to evaluate postoperative changes and responses to therapy. Results seen on CT studies were compared to patients' neurologic status at the time of scanning. The rapid return of the appearance of the brain and the patients' neurologic status to normal soon after evacuation of an uncomplicated epidural hematoma reflect the lack of parenchymal damage. In contrast, acute subdurals are usually produced by associated contusions or cortical lacerations. The mass effect of these parenchymal lesions is responsible for a degree of ventricular shift out of proportion to the usual small size of the acute subdural. Small acute subdurals managed medically and residual collections found after evacuation resolved spontaneously. No acute subdurals progressed to a chronic subdural. The latter are infrequently associated with cerebral parencymal injury and their symptoms are due to the size of the collections. Deformity of the underlying brain by the chronic process and slow re-expansion of the brain account for the common finding of a slowly resorbing, residual fluid collection following surgical evacuation.