Patients undergoing surgery for malignancy are at increased risk of initial and recurrent venous thromboembolism (VTE). Several factors have been found to increase the risk of deep vein thrombosis (DVT) in cancer patients both during the first days after the operation and after discharge from hospital. Although, in general, thromboprophylaxis is provided to cancer patients after surgery, the length of time these patients require prophylaxis has not yet been established. Autopsy series, clinical series, and clinical trials indicate that up to about 40% of VTE occurs post discharge. General surgical patients undergoing major abdominal surgery require VTE prophylaxis, and prolonged thromboprophylaxis should be considered in the post-discharge period in high-risk patients, particularly those with cancer. Evidence from studies in general and orthopedic surgery show that prolonged prophylaxis reduces the number of thromboembolic events after discharge from hospital. Prophylaxis should be simple, safe, and effective and should be administered easily to allow continuation of therapy after discharge. Low-molecular-weight heparins are potentially the most suitable agents for long-term thromboprophylaxis in cancer patients.