Long saphenous vein (LSV) is considered an optimal plastic material for arterial reconstructions in revascularization of the myocardium and in the femoral-popliteal segment. The authors analyze the results from the investigation of the operation material from 12 patients with obliterating atherosclerosis of the lower limbs in which reversed LSV has been previously used for arterial bypass grafts. Material is taken during the second operation performed between two days and 18 months after the first reconstruction. In the early period after LSV implantation into the arterial blood flow there is a prevalence of destructive alterations which are mainly manifested in the intima and internal layers of the media. In later periods a massive layer is formed growing into the venous vascular lumen designated as "néo-intima". Investigations of its structure and of mechanisms of its formation could enable the regulation of this process by clinicists.