The endothelins (ETs) and sarafotoxins (SRTXs) are two structurally related families of potent vasoactive peptides. Although their physiological functions have yet to be precisely elucidated, it seems likely that the ETs are involved in pathophysiological conditions such as hypertension and heart failure. In this minireview, recent advances in the biochemical characterization of the ET/SRTX system, with special reference to structure-function relationships and ET/SRTX receptor subtypes, are described, as well as the recent cloning and expression of ET receptors.