The popliteal artery entrapment syndrome (PAES) is a rare cause of lower-leg claudication due to an anatomic anomaly along the course of the popliteal artery and sometimes, the vein. In the absence of an anatomic anomaly, it is termed 'functional entrapment'. We present 3 patients: a 13-year-old boy with PAES caused by an anomaly of a tendon, a 46-year-old soldier with functional PAES and a 36-year-old male with venous entrapment. Doppler or duplex imaging in patients with PAES generally show no abnormalities, unless entrapment is provoked by plantar or dorsiflexion of the foot. When positive, imaging by CT or MR angiography is advised. In healthy individuals, however, vascular occlusion or stenosis on imaging during provocation testing is considered a physiological finding. Surgery is justified in symptomatic as well as asymptomatic patients with an anatomic anomaly. Surgical exploration of the popliteal fossa should also be considered in patients with functional entrapment, since continuing entrapment may lead to damage of the arterial wall.