Orthopedists have expressed concerns regarding the utility for and applicability to their practices of guidelines from the American College of Chest Physicians (ACCP) for thromboprophylaxis in the settings of total hip and total knee arthroplasty (THA and TKA, respectively). These concerns include the acceptance by the ACCP of venographically assessed asymptomatic deep venous thrombosis as a meaningful clinical trial endpoint and a potential underestimation by the ACCP of the true risk of major bleeding and wound complication in unselected patient populations outside carefully controlled clinical trials. Because symptomatic pulmonary embolism is rare after THA and TKA, the American Academy of Orthopaedic Surgeons has developed a clinical practice guideline focused on preventing this complication while minimizing the risk of bleeding due to pharmacologic prophylaxis. These guidelines are reviewed here.