Studies with MRI have shown differences in corpus callosum size between schizophrenic patients and controls. Most have found that the corpus callosum is smaller in schizophrenic patients, but in only a minority was this finding statistically significant, perhaps due to small sample sizes. Therefore a meta-analysis of 11 published studies of corpus callosum morphology in schizophrenia was conducted to ascertain whether there was a significant difference in corpus callosum size between schizophrenic patients and normal controls. These studies combined comprised 313 patients and 281 controls. Measures of corpus callosum midsagittal area, length, and corpus callosum area:brain area ratio were used in the meta-analysis. There was overall a statistically significant reduction in corpus callosum area in schizophrenic patients compared with controls (P < 0.02). Differences between patients and controls in measures of corpus callosum: brain area and corpus callosum length were not statistically significant. Age and corpus callosum area were related in both patients and controls. The influences on the corpus callosum of overall alterations of brain size, sex, handedness, and psychiatric illness in general remains to be determined.