Schizencephaly is a primary developmental defect of the brain, presumably caused by failure of formation of the cerebral mantle in the regions of the cerebral fissures. Identification has usually been at autopsy in association with severe neurologic abnormalities. The characteristic features of schizencephaly were identified on CT [computed tomography] in 11 patients. Age at detection ranged from an infant at 8 mo. to a 30-yr-old adult. Clinical abnormalities varied from mild to severe, including developmental delays and retardation, microcephaly, focal or generalized motor abnormalities and seizures. CT findings included cerebral clefts, infolding of cortical gray matter along the clefts, an abnormal ventricular system and other associated cerebral anomalies.