Cancer patients in general have a high risk of venous thromboembolic events (VTE) driven not only by patient-related risk factors, but also risk factors related to the disease and anti-cancer therapies. Cancer patients with documented VTE have a notably worse outcome than non-cancer VTE patients. Since VTE is a highly preventable condition, it is striking that large surveys have shown significant underuse of VTE prophylaxis in surgical cancer patients and in medical cancer patients in particular. Recently, guidelines have been issued from European and American medical oncology societies and organizations for identification of cancer patients at risk, and the guidelines give recommendations for treatment of individual groups of cancer patients. This review summarizes the recommendations for VTE prophylaxis and treatment from the recent guidelines and reviews some outstanding issues in VTE prophylaxis and treatment of cancer patients.