40 schizophrenic patients and 17 normal controls underwent magnetic resonance imaging (MRI) of the brain. All subjects were consenting males. The size and form of the corpus callosum in the mid-sagittal cut of MRI were evaluated. This study revealed that the mean size of the anterior region of the corpus callosum was significantly greater in schizophrenics than in controls. The elongated anterior corpus callosum, which did not correlate with age, duration of illness, birth complications or any measures of brain areas in the midsagittal cut, was regarded as a primary change. Schizophrenics with the elongated corpus callosum seemed to have an unfavorable prognosis, because the large corpus callosum suggested poor heterosexual relations, reduced number of hospitalizations, low academic grades and mild anxiety-depression syndrome. A smooth and even corpus callosum seen in schizophrenics was likely a change dependent on duration of illness.