According to the modern views one of the most important factors influencing the outcome of cardiovascular complications of arterial hypertension is the degree of the endothelial dysfunction. The majority of available data are devoted to an estimation of the medications actions. Authors studied the functions of the vascular endothelium according to the rate of the nitric oxide metabolits in plasma at 82 patients with arterial hypertension at including the ozone therapy in basic treatment. The control group included 20 healthy people. There was the initial evaluation, than — next evaluation in 7 days (3 ozone therapy procedures), in 1 month (7 ozone therapy procedures) and in 6 months of treatment. It is found, that using of the ozone therapy in the complex treatment of arterial hypertension of grade I and II improves the outcomes. It is shown in earlier normalization of parameters of arterial pressure, restoration of the metabolic activity of the vascular endothelium due to the increasing of the plasma nitric oxide rate, and it gives stable good outcomes revealed in 6 months of research.