Aim. The study of genetic factors of cardiovascular diseases is of great importance, as the screening of major risk factors that cause the development of cardiovascular accidents across the globe does not enable identifying at least half of those who appear to suffer from the diseases in the future. In order to solve this particular problem, an effect of combined therapy of hypertension on the interleukin 33 (IL-33) in patients who appear to be at high risk of developing cardiovascular diseases as well as the presence of polymorphisms of genes of the folate cycle (MTHFR C677T, A1298G, MTR А2756G, MTRR A66G) have been studied. Methods and results. 41 women suffering from arterial hypertension as well as 10 patients at risk of SCORE<5% were examined. Using the enzyme immunoassay, serum IL-33 concentration before and after 6 months of treatment by combined medication (Noliprel A Forte, Servier) was studied. In addition, all the patients underwent the molecular genetic analysis of blood samples. As the result, the patients with arterial hypertension and ones being at high total cardiovascular disease risk showed the increased concentration of IL-33 in blood. Moreover, the relationship between its concentration in blood and polymorphism of gene MTRR A66G was established. Conclusion. This proves the key role of the polymorphism of gene MTRR A66G in influencing the IL-33 concentration index in blood.