Thromboembolic disease is common in patients with malignant brain tumors and represents a major cause of morbidity and mortality in these patients. The presenting signs and symptoms of deep venous thrombosis and pulmonary emboli can be subtle; thus, a high index of suspicion is required to ensure a timely diagnosis. The accuracy of non-invasive studies of the lower extremities and lungs have significant limitations. Venography and pulmonary angiography remain the best diagnostic techniques when difficult decisions arise regarding the need for anticoagulants in these patients. Patients with malignant brain tumors can be safely anticoagulated with heparin and warfarin, if these agents are monitored carefully. Continuous intravenous infusions of heparin are associated with lower risks of bleeding than intermittent boluses. Clinicians may wish to modify the recommended initial bolus dose of heparin in patients without life-threatening thromboembolic disease. Warfarin reduces the incidence of recurrent thromboembolic events. The incidence of warfarin-related bleeding can be lowered without compromising efficacy by maintaining the PT ratio at 1.3. Potential warfarin drug interactions must be considered, aspirin containing medications and NSAIDS should be avoided, and the platelet count should be kept above 50,000 using transfusions if required to prevent potentially life-threatening bleeding in anticoagulated patients. Thrombolytics are contraindicated in this patient population. Vena caval filters and thrombectomy are rarely required. Additional research is needed to determine the best techniques to prevent deep venous thrombosis and pulmonary embolism in patients with brain tumors.