Forty-two femoropopliteal-tibial bypass grafts were performed in 37 patients. Autogenous vein was used in 15, a composite polytetrafluoroethylene (PTFE)-vein in 15, and PTFE in 12. Two vein grafts occluded acutely because of veins of inadequate size. Three acute occlusions of PTFE grafts were due to primary thrombosis. Whereas no late vein graft occlusions have occurred, eight of 17 composite and eight of 12 PTFE grafts have subsequently occluded. Satisfactory vein grafts do not commonly occlude unless inadequate inflow or outflow exists. Contrariwise, PTFE grafts have an inherent risk of both early and late thrombosis. Therefore, repeated thrombectomy, may be required to maintain PTFE graft patency. Seventeen thrombectomies or revisions of PTFE or composite grafts in 12 limbs have resulted in seven patent grafts, thus underlining the value of this aggressive surgical approach. Composite grafts offer little advantage over PTFE grafts. The role of anticoagulation has yet to be established.