Book excerpt: Since the discovery of endothelin, major advances have been made in understanding the molecular structure and function of the endothelin receptors. At least two subtypes of receptors, designated ETA and ETB, have been identified through biochemical and pharmacological techniques. These subtypes are cloned and expressed and additional subtypes appear to exist. The biochemical events involved in the signal transduction processes that ultimately activate the cellular machinery involved in the end-organ responses are presented, as are the mechanisms by which the receptors recognize specific and different G-proteins. Functions mediated by the receptors at the cellular, tissue and, organ level are reviewed in detail, as well as the roles that they may play a part in the physiologic and pathophysiologic processes in animals and in humans. This book is unique in its breadth of scope. The most recent and important advances, from the intracellular level of the nucleus to the functional effect that endothelin receptors mediate in intact organs, are compiled and reviewed.