Magnetic resonance (MR) was used to examine the cerebellar vermis in 23 patients with schizophrenia and 16 matched controls. MR midsagittal images were processed with computerized image analysis to control partial volume effects as precisely as possible. No between-group differences were found for vermal-to-cerebrum ratio. When gender differences were examined, male patients showed a lower vermal-to-brain ratio than their female counterparts, mainly because of a reduction of the lobules I-V.