Our research is focused on study of changes in the intima-media vascular wall of patients suffering from hypertensive disease as well as patients suffering from hypertensive disease and coexistent extrasystole. We examined 120 patients (42 men and 78 women) between the ages 27 to 81 suffering from hypertensive disease of the II stage as defined by the Ukrainian Association of Cardiologists and extrasystoles (more than 30 episodes per hour of research) of different topography and 30 persons (13 men and 17 women) suffering from hypertensive disease of the II stage between the ages 30 to 76 without rhythm disturbance. The first clinical group was formed of 54 (45%) patients suffering from repeated supraventricular extrasystoles. The second clinical group was formed of 42 (35%) patients suffering from repeated ventricular arrhythmia. The third group was formed of 24 (20%) patients suffering from both repeated supraventricular extrasystoles and ventricular extrasystoles. The results of treatment demonstrate that the existence of repeated supraventricular extrasystoles and ventricular extrasystoles in patients suffering from hypertensive disease of the ІІ stage in contrast to patients without arrhythmia and repeated supraventricular extrasystoles is associatesd with severer vascular dysfunction, which is defined by signs of rather high rigidity of the large arteries (significant reduction of original size of brachial artery diameter), severer defects of endothelium-dependant vasodilation (reduction of increment value of brachial artery diameter during the test with decompression, reduction of periodicity of registration of normal reaction and increase of paradoxical vasoconstriction of the brachial artery during the test with decompression) and significant reduction of general vasodilational potential, increase of frequency of cases with dissociation in the nature of endothelium-dependant and endothelium-independent reaction of the brachial artery. The latter changes were registered in 90 (60.0%) of examined patients, the most frequent of their variants were: 1) reduced reaction of the brachial artery for decompression + normal response in the test with nitroglycerine (29.7%) and 2) paradoxical vasoconstriction in response to decompression + reduced reaction on taking nitroglycerine (22.4%).