Three cases of infragenicular femoropopliteal bypass grafts are presented in which iatrogenic entrapment of the distal portion of the graft occurred between the medial head of the gastrocnemius muscle and the posterior surface of the tibia. The condition should be suspected if ischemia of the leg develops postoperatively when the knee is hyperextended and is improved when the knee joint is flexed. Measurements of the ankle pressure index or Pulse Volume Recorder tracings at the ankle in both flexed and extended positions will confirm the diagnosis. The entrapment of the bypasses in these three patients was easily corrected by transection of the medial head of the gastrocnemius muscle. Relief of the occlusion of the bypass can be easily demonstrated by noninvasive studies.