Normal volunteers (28 women), 20-45 years old, completed tests of visuospatial ability, verbal fluency, and language lateralization, and the midsagittal surface areas of the splenium, isthmus, midregion, and genu of the corpus callosum were measured from inversion recovery magnetic resonance images. Multivariate statistics were used to analyze patterns of correlations. Verbal fluency correlated positively with the area of the splenium and with the area of a posterior callosal factor defined largely by the splenium. The posterior callosum, particularly the splenium, also correlated negatively with language lateralization. There were no other consistent brain-behavior relationships. These results are relevant to understanding factors involved in the development of cognitive characteristics that show sex differences and to understanding the neural basis of language lateralization and verbal abilities.