Venous thromboembolism (VTE) is a major cause of morbidity and mortality in patients with cancer. Primary prevention with pharmacologic agents (or mechanical methods, if anticoagulants are contraindicated) is recommended in all cancer patients hospitalized for surgical or medical reasons. The role of prophylaxis in outpatients is less certain because of the diversity of the patient populations and their cancer treatments with respect to the associated risks of VTE and bleeding. Treatment with low-molecular weight heparin is the recommended first-line approach in cancer patients with newly diagnosed VTE, and is usually continued for a minimum of 3-6 months. Other management issues that require further research include the optimum duration of anticoagulant therapy, the treatment of recurrent VTE, the role of vena cava filters, the effects of VTE and its treatment on quality of life, and the impact of anticoagulants on survival. Newer anticoagulants hold promise in providing more-effective and convenient treatment of VTE in this high-risk population, but further studies are awaited.