The authors analysed the effect of Venarus on the endothelial function in patients suffering from lower limb varicose veins. Our open-label prospective study included a total of 100 patients diagnosed as having CEAP class C1-C2 varicose veins and divided into two equal groups. Dynamic assessment of the clinical course of the disease in Group One patients was carried out on the background of taking Venarus and compression therapy, with Group Two patients evaluated without taking Venarus. At defined stages we determined the level of biochemical markers of endothelial function. The obtained findings demonstrated that the use of phlebotonic Venarus resulted in decreased activity of lipid peroxidation processes and reduced activity of antioxidant system enzymes. Using Venarus was followed by a statistically significant decrease in the concentration of malonic dialdehyde (from 1.220±0.190 μmol/l at baseline to 0.858±0.231 μmol/l after 2 months of treatment), whereas in Group Two patients the changes were insignificant (1.191±0.204 μmol/l before treatment and 1.138±0.175 μmol/l at 2 months thereafter). Patients taking Venarus were also found to have a higher level of nitric oxide metabolites compared with the patients treated by compression therapy alone (51.646±11.757 and 36.310±6.921 μmol/l in Groups One and Two, respectively). Hence, an evidence-based conclusion was drawn that Venarus proved efficient and may therefore be prescribed as pharmacotherapy for correction of endothelial dysfunction.