OBJECTIVE: Previous imaging studies have described focal cortical changes in schizophrenia, with predominant findings of abnormalities in the temporal and frontal regions. The current study hypothesized that cerebellar regions involved in feedback and feed-forward loops with cortical regions affected in schizophrenia would also demonstrate structural changes. METHOD: Using magnetic resonance imaging, the authors measured the volume of individual cerebellar lobules in 19 patients with schizophrenia and 19 healthy comparison subjects. RESULTS: The inferior vermis was significantly smaller in the schizophrenic group than in the comparison group. Patients with schizophrenia also demonstrated a significantly smaller cerebellar asymmetry than the comparison subjects. CONCLUSIONS: The authors hypothesize that these morphometric changes may be developmental in origin and possibly related to cortical abnormalities.