Multiple studies suggest that the corpus callosum in patients with autism is reduced in size. This study attempts to elucidate the nature of this morphometric abnormality by analyzing the shape of this structure in 17 high-functioning patients with autism and an equal number of comparison participants matched for age, sex, IQ, and handedness. The corpus callosum was segmented from T1 weighted images acquired with a Siemens 1.5 T scanner. Transformed coordinates of the curvilinear axis were aggregated into a parametric map and compared across series to derive regions of statistical significance. Our results indicate that a reduction in size of the corpus callosum occurs over all of its subdivisions (genu, body, splenium) in patients with autism. Since the commissural fibers that traverse the different anatomical compartments of the corpus callosum originate in disparate brain regions our results suggest the presence of widely distributed cortical abnormalities in people with autism. (Contains 1 table and 4 figures.)