&NA;We investigated the mechanism of damage to the corpus callosum in a study of 46 brains obtained at the autopsies of patients with head injuries. After correlating the gross findings with the site of impact on the head, we think that such lesions in the corpus callosum are caused by stretching of callosal fibers and/or shearing forces in cases in which lateral movement or twisting of the brain occurs. This mechanism of the dynamic development of callosal injuries is also supported by the retraction bulb formation of axons found histologically in the corpus callosum.