Since the discovery of endothelin in 1988, numerous studies have been undertaken to evaluate their physiopathologic role. There is three types of endothelin ET-1, ET-2 and ET-3, which probably play an essential role in renal and cardiovascular homeostasis. Their principal actions consist in an increase of the arterial pressure, a negative inotrope and chronotrope effect, a coronary vasoconstriction, a decrease in cardiac output and a fall in the renal blood flow and glomerular filtration rate. An elevation of endothelin level has been reported in numerous clinical conditions. However the interest of these descriptions remains unclear. Indeed the absence of pharmacological inhibitors of the synthesis or effect of endothelin prevent the understanding of the interest of these abnormalities. Furthermore the endothelins should not be considered as a hormone but as a paracrine substance.