Saphenous vein is the most widely used conduit for arterial bypass procedures and aneurysms of the vein graft are rare. We report a true aneurysm of a reversed femoropopliteal saphenous vein graft implanted nine years earlier. Duplex ultrasonography identified an aneurysm of the saphenous vein graft and arteriography confirmed this finding. A consideration for endovascular coiling of the aneurysm was entertained, but no proximal “neck” on the aneurysm was present. The patient, therefore, underwent an uneventful resection of the aneurysm with end-to-end anastomosis. Histopathologic examination of the aneurysm demonstrated atherosclerotic degeneration with endothelial disruption, medial necrosis, and fibrous proliferation. The cause of a saphenous vein graft aneurysm is rare and unknown. The management of vein graft aneurysms, however, should be subject to the same criteria that apply to other aneurysms because once vein graft dilation occurs, it is followed by a rapid increase in size, which may lead to possible rupture.