• Enlarged cerebral ventricles in chronic schizophrenic patients suggest a process of mild cerebral atrophy occurs in some. To see if this process involves the cerebral cortex, the widths of the Sylvian fissure, the interhemispheric fissure, and three cortical sulci were measured blindly on computerized tomography (CT) scans of 75 chronic psychiatric patients and 62 asymptomatic volunteers, all less than 50 years of age. A total of 19 of the 60 patients with chronic schizophrenia had at least one abnormality. All 15 patients with other diagnoses were within the control range. Comparing those chronic schizophrenic patients with abnormalities to those without them, there were no significant differences in age, length of illness or treatment, and length of hospitalization. From this and ventricular size data, two thirds of the chronic schizophrenics had some cerebral structural abnormality. Ventricular enlargement did not correlate significantly with cortical abnormalities. Therefore, more than one etiology may account for the structural abnormalities found in chronic schizophrenic patients.