Ahterosclerosis of vessels of the lower extremities is widely distributed in the population. Open surgical revascularization is an efficient method for treatment of this pathology. One of the rare postoperative complications is an anastomosis aneurysm development. We report about a clinical case of a 74-year-old male with a giant (25 cm in diameter) aneurysm of the proximal anastomosis after femoropopliteal bypass. Open aneurysmectomy was performed, and the postoperative period was uneventful.