The objective of the present study was to evaluate the possibilities for the application of ultrasound duplex scanning in diagnostics of the post-thrombotic disease. Material and methods. This article reports the results of the comprehensive treatment of 96 patients presenting with various forms of the post-thrombotic disease (PTD) of the lower extremities with special reference to the comparison of the diagnostic potentials of ultrasound duplex scanning (USDS), X-ray contrast and radionuclide phlebography. In addition, the value of the intraoperative findings for topical diagnostics of the post-thrombotic disease at different levels of venous segments of the extremities was assessed. Results. It was shown that ultrasound duplex scanning is characterized by the high informative value for the diagnostics of the occlusive lesions in deep veins and valvular insufficiency in the infrainvaginal segment with the accuracy, sensitivity, and specificity of 94,2—94,3, 92,8—93,7, 94,7—96% respectively. The results of the ultrasound studies provided a basis for the elaboration of the classification for different types of deep vein recanalization. The qualitative characteristics of the antegrade and retrograde blood flows associated with various forms of the post-thrombotic disease were obtained. The primary role of the great saphenous vein (GSV) was confirmed in the maintenance of the blood outflow in the case of deep vein obstruction. Conclusion. The results of the study indicate that ultrasound duplex studies with the use of colour Doppler mapping (CDM) and energy dopplerography (EDG) provide a reliable information of great diagnostics value about the character, localization, and extension of the changes in deep, superficial, and perforating veins that can be used to control dynamics of the pathological process and determine the quantitative characteristics of the venous blood flow. The types of canalization discovered in this study make it possible to obtain information about the morphological rearrangement of the venous bed, monitor the dynamics of the pathological process, and plan reconstructive surgical interventions on the deep veins of the lower extremities.