The paper presents the results of DEFANS trial (Detralex - assessment of efficacy and safety for combined phlebectomy). The study enrolled 245 patients with varicose vein disease, who underwent unilateral combined phlebectomy. The main group (n=200) received micronized diosmin (Detralex, 1000 mg/day) for 2 weeks before and 30 days after the procedure; control group (n=45) did not receive Detralex in pre- and postoperative period. Pain severity by 10-point visual analog scale (VAS), an area of subcutaneous hemorrhage in the zone of femoral great saphenous vein resection (by original 12-point scale) and subjective feelings of limb heaviness and fatigability were evaluated 7, 14 and 30 days after the procedure. Subjective symptoms and the area of subcutaneous hemorrhage were significantly lower in the main group, then in control: 7 days after the procedure VAS score was 2.9 and 3.5, respectively; hemorrhage area - 3.4 and 4.6 points, respectively. The same trend was observed for limb heaviness and fatigability, evidencing the better exercise and orthostatic tolerance among patients of the main group in early postoperative period. Quality of life assessment by CIVIQ failed to reveal statistically significant difference between main and control groups in 4-weeks postoperative follow-up. Micronized diosmin in pre- and postoperative period after plebectomy helps to attenuate pain syndrome, to decrease postoperative haematomas and accelerate their resorption, to increase exercise tolerance in early postoperative period.