The differences among MRI findings were studied in schizophrenic psychoses. The schizophrenics and atypical psychotics had significant reductions in bilateral hippocampal volumes compared to controls, but the two patient groups did not differ from each other. As for ventricle volume, the schizophrenics showed significantly larger temporal horns and third ventricle than normal controls, whereas atypical psychotics did not. Moreover, the left temporal horn in the schizophrenics was significantly larger than that seen in the atypical psychotics. By cluster analysis, schizophrenics and atypical psychotics were found to have a tendency to be distributed in different groups. These results might be considered to support the classification of schizophrenic psychoses into schizophrenia and atypical psychoses.