Compelling evidence indicates an important role of endothelin (ET)-1 and its receptor subtypes A and B (ET(A) and ET(B)) in the regulation of secretion and growth of the human adrenal gland. ET-1, which is expressed both at the mRNA and at the peptide level in the adrenal cortex, directly stimulates aldosterone secretion in different species, both in vivo and in vitro. This stimulation involves the ET(B) alone and both ET(A) and ET(B) receptor subtypes in rats and humans, respectively. The cellular events coupled to receptor stimulation are currently being investigated. Evidence suggesting a role of the ET system in the regulation of growth of the adrenal cortex, as well as an involvement in the pathogenesis of Conn's adenoma is also available. The purpose of this paper is to review these findings as well as to discuss some future lines of investigation.