The fifth American College of Chest Physicians Consensus Conference on Antithrombotic Therapy provides the most up-to-date guidelines for the prevention of deep venous thrombosis (DVT) and pulmonary embolism (PE) in the surgical patient (1). These recommendations have become a major guideline for clinicians managing patients in the perioperative period. Despite these recommendations, there remains a concern for balancing the risk of major postoperative bleeding with the benefit of preventing thrombosis. In an attempt to resolve this issue, clinicians have requested clear-cut guidelines for identification of high-risk groups for whom prophylaxis must be used. This article will review the etiology, risk-factor stratification, regimens of prophylaxis, and recommendations for prevention of postoperative DVT and PE.