A patient with bilateral entrapment syndrome is reported, he only had symptoms of intermittent claudication with running. The "neutral angiograms" were normal, but the "dynamic angiographies" taken in the sustained active plantar flexion showed a complete occlusion of both popliteal arteries. No abnormalities, no anatomical trap were discovered at the time of surgery. The entrapment syndrome was caused by the muscular hyperdevelopment in this intensively trained athlete. That leads to the concept of "functional entrapment" versus "organic, anatomical entrapment". The diagnostic value of the invasive and non invasive techniques is discussed. Surgical exploration is diagnostic: this is the only means to rule out any organic anatomical entrapment. In a "functional entrapment" surgery may or may not be therapeutic.