Two fatal cases of deep cerebral venous system thrombosis are reported in adults. The first case looked like a diencephalic tumor or encephalitis but the diagnosis was made antemortem by means of cerebral angiography. Autopsy found bilateral infarction of basal ganglia. The second patient presented with a hemorrhagic infarction of right thalamus and basal ganglia. Deep cerebral venous occlusion was diagnosed at autopsy. In spite of a few cases of survival, the thrombosis of the galenic system remains often fatal. The pathological changes and indications for anticoagulation are discussed.