Aim — the aim of our study was to establish an effect of isolated phlebectomy in patients with primary varicose veins on reflux and diameter of incompetent great saphenous vein (GSV) and to assess clinical results of the procedure in terms of recurrence rate of varicose veins. Material and methods. 66 patients (51 women and 15 men) were included and prospectively followed. Age varied from 17 to 71 years. All the patients had primary varicose veins and GSV reflux not lower than the upper third of the calf. Limbs were classified as C2 in 62 (82%) cases, as C2—C3 in 11 (14%) cases, and as С2—C4 in 3 (4%) cases. All the patients underwent isolated phlebectomy under local anaesthesia with preservation of incompetent GSV. All the limbs were assessed with duplex ultrasound on the next day and then in 1 week, 1, 3, 6, 12 months. Reflux was evaluated and diameters were recorded at every control examination. After one year, we estimated the recurrence rate of varicose veins. Results. Persisting of GSV reflux was examined in 58 limbs which were followed up for not less than 12 months. 39 (67%) of GSV were competent within one year after surgery. Diameter of all GSV decreased no matter whether reflux disappeared or not. Recurrent VVs (new visible varicosities) developed on 7 (12%) of the 58 lower limbs after one year. Conclusion. Isolated phlebectomy with a preservation of incompetent GSV leads to the disappearance of reflux in the saphenous axis in 67% of cases. The diameter of GSV decreases significantly in all the GSVs after removing of dilated collaterals. The probability of reflux resolution is significantly higher if the reflux extends not lower than the middle thigh.