Aim — the objective of the present study was to analyse the results of the use of the protocol for the combined out-patient treatment (as an alternative to the in-patient care) with the application of the minimally invasive methods for the management of the patients presenting with the complicated forms of chronic venous diseases. Material and methods. We have undertaken the retrospective analysis of the results of the out-patient treatment of 1302 subjects with the clinical class C4—C6 chronic venous diseases. The 1076 patients comprising the first group (1141 lower extremities) underwent endovenous thermal ablation in the combination with miniphlebectomy. Sclerotherapy was performed on 765 extremities during the postoperative period. In 45 cases, endovasal thermal ablation was performed in the combination with sclerotherapy of the tributaries without miniphlebectomy. The patients of the second group underwent only microfoam sclerotherapy of the main subcutaneous veins, their tributaries, and perforating veins under the echographic control. Varicose veins were diagnosed in 103 patients (134 lower extremities), the recurrence of varicose veins in 69, and post-thrombotic disease in 54 ones. The frequency of recurrent venous ulcers within one year after surgery, the necessity of additional interventions, and dynamics of the clinical results estimated based on the scale characterizing the severity of the disease were used as the criteria for the response to the treatment. Results. The recurrence of the leg venous ulcers within 1 year after surgery was documented in 208 (16%) patients. The venous clinical severity score (VCSS) decreased significantly from 9.9±3.4 to 5.5±3.1 points (p=0.028) in the patients of the first group and from 10.6±4.6 to 5.3±3.6 points in the second group (p=0.037). Additional scleroobliteration of the tributaries and perforating veins was deemed necessary based on the results of the follow-up examinations within 1 year after the treatment in 4% of the patients of the first group and in 31% of those in the second group. Conclusion. The results of the present study give evidence of the high clinical effectiveness of the sclerotherapeutic techniques and thermal ablation of subcutaneous veins in the patients presenting with the clinical class C4—C6 chronic venous diseases.