Acute renal failure occurred in nine cases after cholecystography when a new orally administered contrast medium, bunamiodyl, was used. The patients were four men and five women; their ages ranged from 41 to 71 yr. Four had also received methylglucamine iodipamide intravenously. Oliguria was noted in most cases, and in all there was an acute elevation of serum urea nitrogen. In no case had there been any antecedent condition that would explain the acute renal failure. The severity of renal failure seemed to be related to the total amount of iodine administered, and the "double dose" technique was rarely successful. In tissue obtained at necropsy in the four patients who died and at biopsy in two others, diffuse tubular necrosis was present, and in the four autopsy specimens birefringent green-brown, calcium-containing crystals were noted.