This study's purpose was to present our institution's experience with the use of a risk stratification protocol for venous thromboembolism (VTE) prophylaxis in joint arthroplasty in which "routine" risk patients receive a mobile compression device in conjunction with aspirin and "high"-risk patients receive warfarin for thromboprophylaxis.This was a prospective study of patients undergoing primary or revision knee or hip arthroplasty. Exclusion criteria were patients with a current deep vein thrombosis, history of pulmonary embolism, chronic warfarin therapy, planned multiple surgeries, and prolonged postoperative immobilization. Patients were stratified as either routine or high risk. Routine risk patients received mobile compression devices for 10 days and aspirin twice daily for 6 weeks, whereas high-risk patients received warfarin for 4 weeks and compression stockings for 6 weeks.A total of 3143 total joint arthroplasties were enrolled (2222, 70.7% "routine"; 921, 29.3% "high risk"). The rate of symptomatic VTE within 6 weeks postoperatively was 0.7% (95% CI 0.3%-1.0%) in the standard vs 0.5% (95% CI 0.01%-1.0%) in the high-risk cohort (P = .67), and within 6 months postoperatively was 0.6% (95% CI 0.3%-1.0%) in the standard vs 1.1% (95% CI 0.4%-1.8%) in the high-risk cohort (P = .23). The rate of major bleeding events was significantly lower in the routine (0.4%; 95% CI 0.1%-0.6%) vs high-risk (2.0%; 95% CI 1.0%-3.0%; P < .001) cohort.This study demonstrates that use of a risk stratification protocol allowed the avoidance of more aggressive anticoagulation in 70% of patients while achieving a low overall incidence of symptomatic VTE.