Lower doses of warfarin are effective in the treatment of proven proximal deep vein thrombosis (DVT), and at a substantially lower risk of bleeding complications than with standard doses. The authors compared low-dose warfarin with external pneumatic compression (EPC) boots for prophylaxis against DVT and efficacy and safety in a population of total hip replacement patients at high risk for DVT and bleeding complications. DVT developed in 12 of 72 patients on low-dose warfarin and 11 of 66 patients on EPC. Both regimens were as efficacious as traditional higher doses of warfarin used in prior studies. No major bleeding complications occurred in either group. Low-dose warfarin appears to be an effective and relatively safe form of prophylaxis against postoperative DVT, as does sequential EPC of the calf and thigh.