The medial surface areas of the cingulate gyrus (CG) and other midline structures (corpus callosum, thalamus, lateral ventricle) were examined in 27 traumatically brain injured (TBI) and 12 age- and gender-matched control subjects from an established TBI data base. Significant atrophy, primarily in the posterior CG, was found in TBI patients. Degree of atrophy was related to severity of injury. TBI subjects also had significantly reduced corpus callosum and thalamic cross-sectional surface areas with associated increased lateral ventricular volume, as well as reduced brain volume and increased ventricle-to-brain ratio. Despite significant atrophy of the posterior CG, neuropsychological performance was not related to changes in CG cross-sectional surface area in the TBI subjects. This apparent discrepancy is discussed.