Computerized transaxial tomography was carried out on 50 consecutive unselected patients referred to a neurologic practice for evaluation of focal epilepsy. Structural abnormalities were defined in 35.3 percent of these studies: porencephalic cysts in six patients, diffuse cerebral atrophy in five, cerebral hemiatrophy in three, focal cortical atrophy in two, neoplasms in two, hydrocephalus in one patient, and cerebellar hypoplasia in one. Computerized transaxial tomography is a useful outpatient procedure for evaluation and follow-up of patients with focal seizure disorders.