The corpus callosum (CC), has been hypothesized to be implicated in the pathogenesis of schizophrenia; however, the findings from magnetic resonance imaging studies are conflicting. Moreover, the relationship between first-rank-symptoms (FRS) and CC abnormalities in schizophrenia is yet to be examined. The authors examined CC morphometry, based on Witelson's method, in antipsychotic-naïve-schizophrenia patients in comparison with matched healthy-control subjects. Patients had significantly smaller CC, splenium, and isthmus areas than control subjects. A novel finding of the study is that only those without FRS differed from control subjects, but not those with FRS. Study findings support a neuro-developmental hypothesis and possible connectivity abnormalities in symptom-genesis.