Endothelins are peptide tissue hormones with a powerful vasoconstrictor effect. The most important one among them, endothelin-1, is the most powerful vasoconstrictor substance in the human organism which causes constriction of the blood vessels, in particular renal, coronary, pulmonary and cerebral arteries, bronchioles, and inhibits the secretion of atrial natriuretic factor and vasopressin. Because of these effects importance in the pathogenesis of some diseases is ascribed to it, e.g. myocardial infarction, cardiac failure, asthma bronchiale, Raynaud a syndrome, renovascular disease, cyclosporin-induced nephrotoxicity and cerebrovascular attacks. Although there is little direct evidence on the role of endothelins in arterial hypertension, some authors prove its importance at least in some of its forms, e.g. salt sensitivity, or in complications of hypertension. The results of experimental and human studies with antagonists of endothelin receptors and endothelin-converting enzyme blockers also support the role of endothelin in the pathogenesis of hypertension. The use of these antagonists in the treatment of hypertension calls however for further long-term studies.