The microsurgical anatomy of the deep venous system of the brain was examined in 20 cerebral hemispheres. The deep venous system is composed of the internal cerebral, basal, and great veins and their tributaries. This system drains the deep white and gray matter surrounding the lateral and 3rd ventricles and the basal cisterns. The deep veins are divided into a ventricular group composed of the veins converging on the walls of the lateral ventricles and a cisternal group that includes the veins draining the walls of the basal cisterns. The internal cerebral vein is included in the ventricular group because it is predominantly related to the ventricles, and the basal and great veins are reviewed with the cisternal group because they course through the basal cisterns. The choroidal veins are included with the ventricle veins because they arise on the choroid plexus in the ventricles. The thalamic veins appear in both the ventricular and the cisternal groups because some course on the ventricular surfaces and others course in the basal cisterns. The operative approaches to the major trunks in this system are reviewed.