The basic physiological functions of the endothelium are functions of a semipermeable membra- ne, control of optimal vascular patency and safeguarding of the vascular integrity. Endothelial dysfunction may be considered the first functionally important stage of atherosclerosis. The most frequent evoking factors include hyperlipoproteinaemia, arterial hypertension, smoking and dia- betes mellitus. The clinically most important manifestations of impaired endothelial function are disorders in the coronary circulation and transient cerebral ischaemias. Ways of detection of endothelial dysfunctions include invasive methods and at present non-invasive ultrasonic met- hods. Treatment of endothelial dysfunction is based on elimination of the basic risk factors of atherosclerosis, i.e. elimination of active and passive smoking, in indicated cases strict dietetetic and pharmacological hypolipidaemic treatment, effective antihypertensive treatment and com- pensation of DM.

        Key words: Endothelium - Endothelial dysfunction - Ultrasonography of peripheral arties - Risk