Postoperative orthopaedic patients remain at risk for venous thromboembolism (VTE) after hospital discharge. Therefore, the authors designed and implemented a program for prevention of VTE that included outpatient adjusted-dose warfarin using twice-weekly prothrombin time (PT) determinations, a dedicated telephone line for PT results, and vigilant nurse-physician supervision to administer prophylaxis to 125 postoperative orthopaedic patients against VTE for an average of 31.4 days after discharge. PT was maintained between 13.2 and 18.3 seconds (1.1-1.5 x control) in the average patient. There was a failure rate of 3.2% and 0.8% for clinically suspected and radiologically confirmed deep venous thrombosis (DVT) and pulmonary embolism (PE), respectively. The rate of bleeding complications was 3.2%, but none of these patients required transfusion or hospital readmission for hemorrhage. The authors conclude that the described program for VTE prevention is a safe, effective, and practical program to administer prophylaxis to postoperative orthopaedic patients against clinically evident VTE for the first month after hospital discharge.