A retrospective study was made of 226 psychiatric patients. Only 74 patients (33%) did not show abnormalities on the CT-scan. The most observed CT-scan abnormality was cerebral atrophy (65%). Atrophy was observed especially in schizophrenia, dementia and addiction. The frequency of atrophy in schizophrenic patients increased with the patient's age. Focal lesions were observed especially in patients with an affective psychosis, dementia of with an organic psychosis. In the presence of neurological, neuropsychological or only EEG abnormalities the number of focal lesions increased threefold. Left-side hemisphere lesions occurred twice as often as right-sided lesions.