Arterial hypertension is one of the major risk factor for atherosclerosis. Besides elevated blood pressure hypertonics, have a lot of other risk factors because hypertension is a part of endocrine metabolic syndrome. Therefore these patients are even more in danger of cardiovascular diseases. Preventive measures are most successful in the early stages of atherosclerosis, that is way early the early detection of the changes accompanying atherosclerosis is important. The aim of the study was focused on the changes in arterial wall and changes in blood structure which influence blood rheology. Intima - media thickness (IMT) of carotid arteries, flow - dependent vasodilatation and plasma viscosity have been determined. IMT has been detected by B mode ultrasound technique at three different locations. Flow dependent vasodilatation has been evaluated by a provocation test on a brachial artery. Blood samples have been taken in order to determine plasma viscosity and the factors that influence atherogenesis. 28 hypertonics being treated with ACE inhibitors (mean age 55,1) and 22 healthy individuals (mean age 54,2) with no risk factors for the atherosclerosis participated in our study. (Abstract truncated at 2000 characters).