Structural and functional brain imaging have contributed significant data to our understanding of schizophrenia, but we are still unable to understand the presumably heterogeneous neuronal dysfunctions of schizophrenic disorders. Current disease models define schizophrenia as an exclusively forebrain disorder. Nevertheless, morphological and functional data support the authors' view that cerebellar dysfunction may contribute to schizophrenic disorders. This article presents a critical review of neurological signs, including results of a clinical study performed by the authors, as well as postmortem and neuroimaging findings of cerebellar pathology in schizophrenia patients and studies on other psychiatric features associated with cerebellar lesions. In addition, anatomical, physiological, and behavioral data are reviewed that argue in favor of cerebellar involvement in nonmotor brain functions. A particular cerebellar region, the anterior vermis and corresponding fastigial nucleus, is assumed to be important in schizophrenic disorders, and the neurochemistry and vermian-fastigial-forebrain pathways are shown to correspond well with current hypotheses on neurotransmitter imbalances in schizophrenia. Therapeutic implications are outlined.