Twenty patients treated by femorofemoral bypass were retrospectively reviewed to determine if femorofemoral bypass was efficacious in the treatment of disabling claudication. The data have clearly demonstrated that two criteria are necessary for the successful outcome of femorofemoral bypass. First, the donor artery should be hemodynamically normal in order to support the recipient limb. This can be determined by either a normal treadmill exercise test result or by a normal preoperative intraarterial papaverine test result. Second, the patient's functional improvement will be dependent on the status of the runoff vessels in the recipient limb; therefore, many patients with patent superficial femoral and popliteal arteries will have excellent results (50 percent in this series), whereas those with occluded superficial femoral or popliteal arteries or both will have less improvement (40 percent in this series). Therefore, femorofemoral bypass should be used in the treatment of intermittent disabling claudication in the properly selected patient.