The existence of the fourth perforating artery of Paturet [7], a collateral branch of the superficial femoral artery in its lower third, is the subject of much debate. This artery has so far only been the subject of radio-anatomic descriptions based on arteriographies carried out within the context of arteriopathy of the lower limbs. We present a descriptive anatomic study of this artery based on 14 observations on 32 dissections. Three types of approach were carried out: exposure of the artery of the femoral quadriceps muscle up to its ending in the vastus lateralis; a lateral "orthopaedic" approach to the lower third of the femur; and a "vascular" approach by a medial incision to the femoro-popliteal axis in the lower third of the thigh. Its main relations are described, passing in front of the superficial femoral vein and then behind the femur before ending at the vastus lateralis muscle. These relations explain the possibility of anastomoses with collateral or terminal branches of the deep femoral artery (vastus lateralis artery, third perforating artery). The fourth perforating artery of Paturet [7] must be protected in traumatologic and vascular surgery. It is the main collector of vascular anastomoses between the deep femoral artery and the femoro-popliteal axis in the event of proximal occlusion of the superficial femoral artery. Its removal, in such a case, can aggravate an underlying arteriopathy.