OBJECTIVE: Since previous work indicated smaller than normal temporal lobe structures in schizophrenic patients, the authors tested the hypothesis that this abnormality might be reflected in abnormally large sylvian fissures. METHOD: The subjects were 48 schizophrenic patients and 51 normal comparison subjects matched groupwise with regard to age and sex. CSF spaces (sylvian fissures, temporal lobe sulci, temporal horns, third ventricle, lateral ventricles, and superficial cerebral sulci) were visually assessed with the magnetic resonance imaging rating protocol of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). RESULTS: The sylvian fissures of the schizophrenic patients were found to be bilaterally wider than those of the comparison subjects. There were no other significant differences. CONCLUSIONS: Schizophrenic patients appear to have larger than normal sylvian fissures, which may reflect smaller superior temporal gyri.