OBJECTIVES: We assessed the real-world anticoagulation thromboprophylaxis patterns in patients undergoing major orthopedic surgery. METHODS: A retrospective study (January 1, 2005 - December 31, 2007) was conducted using a large hospital database linked with outpatient claims. Patients’ demographics, and clinical and provider characteristics were compared using Chi-square testing and standardized differences. Risk-adjusted event rates were estimated using the Poisson regression model. RESULTS: The linked database is comprised of 2280 enrollees, of whom 1769 met the eligibility criteria. A total of 1552 patients received anticoagulant venous thromboembolism (VTE) prophylaxis; 264 of these patients received a combination of low molecular-weight heparin and warfarin. Of these patients, 105 (40%) were switched between the two monotherapies, whereas 159 (60%) received bridge (overlapping) prophylaxis. VTE and major bleeding events were significantly lower for bridged patients.  However, duration of bridging varied widely. CONCLUSIONS: Although there is a benefit with longer duration of therapy, duration of anticoagulation bridging therapy varies widely and does not appear to be consistent with published guidelines.