MRI scan reports from 536 psychiatric inpatients in 10 DSM-III-R diagnostic categories and 51 normal control subjects were reviewed for incidence and severity of four types of abnormality: deep white matter hyperintensities, periventricular hyperintensities, ventricular enlargement, and cortical atrophy. Multivariate analysis revealed significant effects for both diagnosis and age and a significant interaction. After age covariance, the most discriminant type of abnormality was ventricular enlargement, with normal control subjects having significantly less enlargement than 6 of 10 patient groups, including the personality disorder and the depressed nonpsychotic groups. The data also suggested important diagnosis by age by type-of-abnormality interactions deserving of further study.