Changes of the human corpus callosum in normal aging and Alzheimer's disease were analysed by means of morphometry. A standardized computerized evaluation program was implemented allowing objective, quantitative and reproducible data. The various parts of the corpus callosum showed a different pattern of changes in normal aging as compared to Alzheimer's disease. In conclusion, in normal aging affects mostly the front-temporal interhemispheric fiber systems, whereas in Alzheimer's disease the parietotemporal commissural fibers are altered.