Patients with malignant disease constitute a significant subgroup among patients with venous thromboembolism. Current results suggest that cancer patients are not only at an increased risk for thromboembolic events, particularly during chemotherapy treatment or after surgery, they also have an increased risk for bleeding complications while receiving oral anticoagulant treatment. The exact incidences of venous thromboembolic complications for the various types of cancer, however, are not well determined. Recent studies have indicated that subcutaneous low-molecular-weight heparin (LMWH) is as safe and effective as intravenous unfractionated heparin (UFH) in the initial treatment of venous thromboembolism. Moreover, a meta-analysis has provided preliminary evidence that, compared with UFH, LMWH treatment may prolong survival in cancer patients. Initiation of LMWH treatment in these patients is, therefore, recommended. Prospective randomized clinical trials to assess the optimum dose and duration of therapy are called for.