Polytetrafluoroethylene bypasses were used in a series of 56 reconstructions, to the popliteal artery in 45 instances or below in 11 instances. These were performed in high risk situations in patients who usually did not have a suitable saphenous vein. Autologous saphenous vein bypass grafts were performed in a comparable series of 56 high risk situations. The polytetrafluoroethylene reconstruction was patent at 4-14 mo. in 43 of 45 patients having femoropopliteal bypasses, with limb salvage in 39 of the 45. The saphenous vein bypass was patent at 8-14 mo. in 39 of 45 patients having femoropopliteal reconstructions, with limb salvage in 36 of the 45. Distal-small vessel-bypass patency rates were similar for reconstructions with polytetrafluoroethylene and saphenous vein. No increase in the number of deaths or complications was observed in the polytetrafluoroethylene group, but a general reduction was noted in the operating time and in the incidence of wound complications. These results justify the continued used of polytetrafluoroethylene grafts in patients without saphenous veins who require arterial reconstructions of the lower extremity for limb salvage. The exact place of polytetrafluoroethylene grafts in reconstructive surgery of arteries in the lower extremity awaits definition based upon longer periods of observation.