The present investigation included 65 patients (36 men and 29 women of the mean age of 51.3±6.7 years) presenting with grade I-II arterial hypertension (AH) and undergoing intravenous ozone therapy in combination with the intake of antihypertensive preparations. ECG studies showed that a course of ozone therapy decreases the degree of in homogeneity of intra-myocardial electrophysiological processes in the patients with AH as apparent from reduced dispersion of P-wave and corrected QT-interval. Analysis of the results of high-resolution ECG revealed a significant decrease in the frequency of ventricular late potentials from 29.2% (19 patients) to 13.8% (9 patients) (χ2=4.5; p=0.03) whereas the decrease in the frequency of atrial late potentials was insignificant, from 40% (26 patients) to 29.2% (19 patients) (χ2=1.67; p=0.19). The results of spectral-temporal mapping indicate that a course of ozone therapy resulted in a significant decrease of the total number of local peaks in the QRS complex and the number of peaks with low-amplitude and high-frequency characteristics.