Major surgery is associated with increased risk of venous thromboembolism (VTE), which is decreased by anticoagulant drugs. Evidence is growing that major surgery is associated with increased risk of arterial thrombosis (AT). With the aim of testing aspirin ability in reducing the risk of post-operative AT, we performed a systematic review of studies in which acetylsalicylic acid (ASA) was compared to anticoagulant drugs in VTE prophylaxis of patients undergoing total hip replacement (THR) or total knee replacement (TKR).