The authors have performed an experimental and clinical assessment of a new graft. In 37 mongrel dogs 49 experiments were carried out with the implantation of grafts "Vitaflon" into different parts of the arterial and venous bed. It was shown that the domestic graft from modified polytetraftoroethylene had high biological inertia, good plastic properties, zero surgical porosity, strength and reliable "taking" by the recipient's organism. Following the experimental work the prosthesis "Vitaflon" (30-50 cm long and 8 mm diameter) was implanted in the femoro-popliteal-tibial position to 15 patients suffering from obliterating atherosclerosis of the lower extremity arteries. The period of follow-up observations was about 12 months. Thrombosis took place in two grafts in the early postoperative period. Other shunts were functioning well which was confirmed by the clinical picture and dopplerography.