In 1986 Nasrallah and colleagues found that increased thickness of the corpus callosum may be specific to right-handed female schizophrenics. Male and female right-handed schizophrenics were compared with normal and psychiatric controls of comparable age, sex, education, and social class on measures of callosal thickness from a midsagittal magnetic resonance imaging cut and neuropsychological tests of interhemispheric transfer. The sex difference in anterior and posterior callosal thickness in normal controls was reversed in schizophrenics, with the corpus callosum being thicker in female schizophrenics and thinner in male schizophrenics. Similar findings were also observed in the psychiatric control group. These structural differences were not paralleled by evidence of impaired interhemispheric transfer on neuropsychological tasks. These results support the finding of sex-dependent callosal abnormalities in schizophrenia but indicate that these abnormalities may not be specific to this illness.