The purpose of the present study was to determine the duplex scanning (BS) potential for the evaluation of the results of reconstructive operations for postthrombotic disease. We examined 89 patients who underwent different reconstructions on the deep veins of the lower extremities. The operations included crossover vein graft in unilateral occlusions of the iliac veins (36 patients), bypass grafting in occlusion of the femoral and popliteal veins (12), transposition (23) and autotransplantation (18) of the venous segments containing good valves in recapitalization of the deep great veins. Ultrasound diagnosis of the patency of the veno-venous grafts and function of the transposed or transplanted valves had an accuracy of 100%. DS has been demonstrated to compare very favourably with contrast phlebography. We present the functional characteristics of the blood flow in the veno-venous bypasses when the patient is in the horizontal and vertical positions at rest and under conditions of hydrodynamic provocation of the retrograde blood flow at Valsalva's test, compression tests and of the antegrade blood flow at physical exercise. The tests which upgrade the effectiveness of ultrasonography have been worked out. The morphological variants of lesion of the transplanted venous valve cusps have been established. It is demonstrated that the main cause of valvular incompetence of autotransplants lies in supravalvular (sinusoidal) thrombosis which develops in the early postoperative time, thereby giving rise to the block of the cusps of a transplanted valve. The data on the hemodynamics of venous autotransplants, obtained in the course of the study enable one to select an optimal variant of reconstructive operation, to delineate the postoperative treatment policy and to predict the results of surgical intervention.