About 15% of patients with cancer have cerebrovascular lesions, resulting from 4 kinds of disorders sometimes intermingled in advanced disseminated cancer: coagulation disorders, direct effects of the tumor, infections and therapeutic measures. Infarction, hardly less frequent than hemorrhage, mostly complicates lymphoma and carcinoma. Hypercoagulation states, such as chronic disseminated intravascular coagulation, nonbacterial thrombotic endocarditis, and nonmetastatic cerebral venous thrombosis account for about 50% of cases. Tumor emboli, as seen in intravascular malignant lymphomatosis, arteritis related to aspergillus, granulomatous angiitis with or without herpes zoster and radiation-induced atherosclerosis are rarer. Cerebral hemorrhages, excluding bleeding from the metastases of choriocarcinoma and melanoma are mainly associated with leukemia by acute disseminated intravascular coagulation as in promyelocytic leukemia, by leukostasis or by pancytopenia. Both infarction and hemorrhage rarely reveal the neoplasia. Lesions are often small and disseminated, and therefore produce a picture of diffuse acute or subacute encephalopathy rather than acute focal deficits. Finally, there may be no relationship between the cerebrovascular event and the neoplasia, and atherosclerosis or traumatic subdural hematoma may well be the causal factor.