Investigation of the dynamics of heart rate variability (HRV) in anti-hypertension therapy can facilitate the evaluation of the effectiveness of treatment. AIM OF INVESTIGATION: to compare anti-hypertension effect of monotherapy with nebivolol and dilatrend with dynamics of HRV and the estimation of the state of patients with mild arterial hypertension (AH) and metabolic syndrome (MS). MATERIAL AND METHODS: HRV was studied in 42 patients with mild AH and MS at the age of 32-60. Eighteen of them were treated with 5 mg of nebivolol during 24 weeks, and twenty-four with 25-50 mg of dilatrend during 16 weeks. All the patients were subjected to 24-hour ECG monitoring with analysis of HRV and arterial pressure (AP) before and after treatment. The main feature of HRV analysis was investigation of dependence of sinus arrhythmia on the mean value of heart rate (HR) RESULTS: With nebivolol treatment AP decreased in 11 patients, HRV became better in 9 patients. 7 cases manifested coincidence of AP reduction and HRV improvement. In 6 cases out of 7 when AP did not decrease, HRV did not change. Worsened HRV was observed in 3 cases: in one case with growing AP and in 2 cases with decreasing AP. All the patients, except one, regarded their state as improved. With dilatrend treatment AP lowered in 16 cases. In 9 cases HRV became better, in 11 cases it remained the same, and in 4 cases it became worse. Positive HRV dynamics in 7 cases out of 9 was accompanied by lowering of AP, while negative dynamics was observed in one case with rise of AP and in three cases with very low AP or in the absence of AP dynamics. 14 patients felt better, 6 of them manifested better level both of AP and HRV. CONCLUSION: The method of 24-hour HRV analysis based on assessment of dependence of the value of sinus arrhythmia on HR is useful in evaluating the effectiveness of anti-hypertension therapy. As a rule, an effective decrease in AP is accompanied with improvement of HRV. The absence of improvement of deterioration of HRV in anti-hypertension therapy is a factor which should be taken into consideration when choosing the mode of therapy.