The main topic of the article is the assessment of the endothelial dysfunction and the rigidity of arterial wall in the small, medium and large vessels in young patients with short anamnesis of hypertension and with different variability of blood pressure (BP). In young patients even at the beginning of arterial hypertension (AH) the disturbance in rigidity of arterial walls in great and peripheral vessels occurs. The increased variability of BP in young patients with AH is an aggravating factor of the arterial rigidity disturbances. The assessment of arterial rigidity in young patients at the early stages of the disease can elicit the early signs of endothelial dysfunction