Venous thromboembolism continues to be a major source of morbidity and mortality in both elective and traumatic orthopedic surgery. Prevention of this complication has received much attention in the orthopedic literature in recent years. We reviewed the relative efficacy and safety of various agents in the prophylaxis of venous thromboembolism arising after major orthopedic surgery. In patients undergoing total hip replacement, low-molecular-weight heparin in fixed doses, adjusted doses of warfarin, and unfractionated heparin in adjusted doses are the most effective prophylactic agents and are highly recommended for routine use. Low-molecularweight heparin or warfarin should be used in patients with hip fractures. Low-molecular-weight heparin, warfarin, or intermittent pneumatic compression should be used in patients undergoing major knee surgery. A number of questions still remain unanswered. In particular, further studies are needed to establish the optimal duration of prophylaxis.