The anatomical and histological structure of Corpus callosum is analysed, mainly in relation with cell composition and fibre distribution. The vascularization of Corpus callosum is analyzed in relation with the distribution of the supplying arteries and the fine organization of small vessels. The first part of the presentation deals with damages of corpus callosum as a consequence of hemorrhagic and ischemic vasculopathies. The lesions may be direct or indirect; the latter follow the distruction of hemispheric areas interconnecting through the corpus callosum or occur as the product of reduced flow in the territories of carotid and vertebral arteries. A special mention is dedicated to the anatomoclinical syndromes developing after damages to the anterior or posterior section of Corpus callosum. The second part deals with specific diseases such as Marchiafava-Bignami's disease, which is treated as an example of glial cell pathology and chronic edema. The third part deals with tumors. Besides lymphomas which need a separate consideration for their modality of growth, neuroepithelial tumors are discussed. The most important problem is that of invasion through the Corpus callosum. The cell traffic in this structure with all the connected questions about cell migration, adhesiveness and motility are presented. Pathology of Corpus callosum is extended also to anatomically related median structures such as fornix and septum pellucidum. The latter is one of the principal pathways of diffusion in gliomas.