To study the incidence of venous thromboembolism (VTE) following the surgical treatment of the patients presenting with primary varicosis and to elucidate the potential risk factors of this condition. The present cross-sectional study included 278 patients with primary varicosis who had undergone phlebectomy. All of them were examined by ultrasound scanning of the venous vessels in the lower extremities within 3-7 days after the surgical intervention. Fifty one (18.3%) patients suffered deep vein thrombosis (DVT) in the early postoperative period. In 45 (88%) of them, DVT was confined to crural veins, in the six (12%) remaining ones the popliteal vein was affected too. The clinical manifestations of pulmonary thromboembolism were not observed in the present study. The potential risk factors of VTEC included: female/male sex (odd ratio (OR) 1.10, 95% confidence interval (CI) 0.57-2.12), age above 40 years (OR 1.31 95% CI 0.69 - 2.49), age above 60 years (OR 1.01, 95% CI 0.36-2.82), duration of the disease over 5 years (OR 1.07, 95% CI 0.58-1.96), body mass index >30 (OR 1.07, 95% CI 0.48-2.37), duration of surgery (OR 1.21, 5% CI 0.62-2.34). The results of statistical analysis do not confirm the influence of these factors on the probability of venous thrombosis. Combined phlebectomy is by itself the sole significant risk factor of the development of venous thromboembolic complications. The patients admitted to a hospital for phlebectomy should be regarded as belonging to a group of moderate risk of VTE which implies the application of the proper measures to prevent thrombosis.