In the past year, major advances have been made in understanding the role of endothelin peptides in renal homeostasis. Numerous cells in the kidney secrete endothelin, which binds to two receptor subtypes on neighboring cells in an autocrine or paracrine mode. Endothelin is a potent vasoconstrictor of the renal vasculature that reduces renal blood flow and glomerular filtration rate. Endothelin also affects renal sodium and water handling. Finally, we may have to extend our concept of the renal actions of endothelin to include its growth factor actions.