A prospective randomized trial compared the effectiveness of low-dose warfarin (LDW) to sequential compression devices (SCD) for deep venous thrombosis (DVT) prophylaxis in 95 patients after total hip arthroplasty (THA). Patients were 39 years of age or older, with no history of previous venous disease. Bilateral lower-extremity venography was used for thrombi detection. Venous thrombi occurred in 12 patients (all calf) on LDW (26.6%) and 3 patients with SCDs (one calf, two thigh) (6.0%). The incidence of DVT was significantly higher in the LDW group (P less than .006). In this study of average-risk patients, the use of SCDs significantly outperformed LDW as a prophylactic agent. However, the thrombi that did occur with SCDs were more critical.