Objective. To study a relationship of arterial hypertension (AH) severity with the cerebral blood flow and structural changes in the brain matter, processes of lipid peroxidation and antioxidant defense, parameters of homeostasis, indicators of endothelial dysfunction and apoptosis. Material and methods. A complex study of 84 patients with AH, aged from 43 to 64 years, was carried out. Results and conclusion. The severity of atherosclerotic damage increased with the increasing of the AH degree. There were the sings of cerebral atrophy, changes in the white matter of brain hemispheres accompanied by the increase of oxidative stress and insufficient antioxidant activity, appearance of procoagulation shifts in the homeostasis system, along with the moderate activity of fibrinolysis, increase in the level of proinflammatory cytokines and markers of apoptosis, endothelin-1, decrease in nitrogen oxide concentration.