Venous thromboembolism is a serious complication in patients with cancer. The seriousness of venous thromboembolism as a complication in cancer patients is becoming recognized as an important medical issue. Venous thromboembolism is a multifactorial disease associated with vascular endothelial damage, stasis of blood flow, and hypercoagulation. Preexisting morbidity, mutations of factor V Leiden or prothrombin 20210A, type of cancer, presence of metastases, use of central venous access, surgery, anesthesia, etc., increase the risk of venous thromboembolism. The patients with malignancies have a 7-fold increase in the risk of venous thromboembolism compared with individuals without cancer. Venous thromboembolism is the second most common cause of mortality in cancer patients. Venous thromboembolism is the most common cause of death at 30 days after surgery in patients undergoing surgery for cancer. Venous thromboembolism caused death in 46.3% of the cases after surgery for cancer. The Geneva prognostic index identified predictive factors for an adverse outcome, and the American College of Chest Physicians (ACCP) has suggested the guidelines for the prevention of venous tromboembolism in cancer patients. Cancer patients should receive appropriate venous thromboembolism prophylaxis. The methods used for venous thromboembolism prophylaxis are mechanical, pharmacological, or a combination of both. Well-timed thromboprophylaxis may protect patients from venous thromboembolism, early lethal outcome and even influence survival.