A modified program of intravenous hyperalimentation therapy was instituted for a 71-year-old patient following the development of renal failure after abdominal aortic aneurysmectomy. A prolonged postoperative ileus precluded adequate oral feedings for a total of three weeks, and a progressive rise in blood urea nitrogen (BUN) and serum creatinine levels suggesting nonoliguric acute tubular necrosis precluded the use of protein hydrolysates intravenously. A solution of eight essential amino acids in their L forms in a mixture of 50% dextrose and vitamins was administered by constant 24-hour superior vena cava infusion by standard techniques. Not only did stabilization of the rate of rise of Bun occur and dialysis was not required, but a significant decrease in serum levels of potassium, magnesium, and phosphate occurred in the absence of increased urinary or fecal losses. These biochemical responses suggested incorporation of these ions and nitrogenous wastes into structural protein.