Intermittent claudication in the young is unusual. The most common cause is premature atherosclerosis; however, conditions such as thromboangitis obliterans, embolism, trauma, cystic disease of the adventitia or popliteal artery entrapment are diagnostic considerations.Entrapment of the popliteal artery by an anomalous muscle attachment or fibrotic band may result in external compression of the popliteal artery. Such compression can cause acute ischemia, and over a period of time the artery may develop irreversible changes secondary to repeated trauma. Certain aspects of the symptoms complex may serve to alert one of the possible presence of the popliteal artery entrapment syndrome. The following case is illustrative.J. T., a 28-year-old white male construction worker was referred to University of Wisconsin Hospitals for evaluation of hypertension and recurrent pain in his left calf and foot of one year duration. The pain was described as crampy and precipitated primarily by walking while rest afforded almost immediate relief. He had also noted that the left foot was cooler and more sensitive to cold than its counterpart. Positive physical findings other than an elevated blood pressure of 170/120 mmHg were limited to the left leg. A bruit, accentuated by exercise, was present over the left popliteal fossa. Both femoral pulses and those in the distal right lower extremity were normal. The pulses in the left foot were 3 + on a scale of 5. With exercise (walking in place till pain commenced) all foot pulses disappeared and slowly reappeared following rest.Renal arteriography was normal excluding renal vascular hypertension. Arteriography of the left lower extremity with the leg extended showed the vessels to be normal except for a 2.8 cm segment of the popliteal artery in the intercondylar fossa. The arterial wall was smooth; however, the vessel had an extrinsic pressure defect along the lateral aspect. This resulted in minor displacement of the artery medially but compromised the lumen approximately 90%. No poststenotic dilatation was present (Fig. 1).The popliteal fossa was explored through medial incision. A fibrous band was seen to extend from the medial head of the gastrocnemius muscle to the lateral femoral condyle. This crossed the popliteal vessels and caused compression of the artery. Following removal of the band, normal pulses were restored in the foot. Externally, the artery appeared to be normal. An operative arteriogram showed only minor residual compression of the wall and that area appeared to be smooth. Two centimeters distal to the tibial plateau there was