A meta-analysis of 16 randomized trials (38747 patients) was conducted to investigate the effects of new oral anticoagulants (rivaroxaban, dabigatran, and apixaban), compared with standard enoxaparin, for prophylaxis against venous thromboembolism after total hip or knee replacement surgery. After investigating relative risks of symptomatic venous thromboembolism, clinically relevant bleeding, and deaths, the anticoagulants did not differ in net clinical endpoint (a balance of efficacy and safety). Generally the results demonstrated that the higher the efficacy of a treatment, the higher the risk of bleeding tendency.