Abstract The aim of the present study was to investigate the variation in cerebellar morphology in schizophrenia and alcohol dependence. Volumetric measurements of cerebellar structures were performed using magnetic resonance imaging in 17 men with schizophrenia, nine men with alcohol dependence, and 18 healthy men. Schizophrenia patients had smaller volumes of the posterior superior vermis, while alcohol-dependent patients had smaller volumes of both the anterior and the posterior superior vermis compared with controls. The groups were not significantly different with respect to cerebellar hemisphere volumes. The results provide indications for differential morphological abnormalities of the cerebellar vermis in patients with schizophrenia and alcohol dependence.