Three groups of patients were available for the observation. Group 1 (n=45) was comprised of the patients presenting with post-thrombotic changes in deep veins diagnosed with the help of the ultrasonic scanning technique. Group 2 included patients (n=37) with post-thrombotic syndrome (PTS), and group 3 involved patients with (n=40) long-standing primary varicosis who never before experienced thrombosis (according to the results of clinical and ultrasound studies). It was shown that the development of thrombosis in tibial and popliteal veins in patients with primary varicosis (PV) contributes to the evolvement of severe disturbances in venous hemodynamics and leads to the development of conspicuous clinical signs and symptoms.