Acute renal failure occurred in a patient with a carcinoid syndrome whenever he developed a flushing episode. Renal biopsy performed during one of these oliguric episodes did not reveal any lesions which could explain this reversible form of renal insufficiency. Urinary indices were not conclusive. Alteration of intrarenal hemodynamics by vasoactive compounds is proposed to be the causative mechanism of this relapsing acute oliguric renal failure.