Acute renal failure in the surgical patient is accompanied by a state of hypermetabolism and increased catabolism. Nutritional therapy is therefore directed at the preservation of body cell mass and protein synthesis for repair of wounds and damaged renal tubuli and for maintenance of host defense mechanisms. We examined the effect of two levels of protein intake (18.4 +/- 1.4 and 30.8 +/- 2.4 mg N/100 g BW/day) and three different amino acid formulations (Freamine III, Nephramine, and a made-up mixture of Nephramine + Freamine HBC) on renal function following mercury chloride-induced acute renal failure in the rat. All animals suffered severe renal failure manifested by increased plasma urea and creatinine levels, decreased creatinine clearance, and increased fractional excretion of sodium. On day 4 of acute renal failure, rats receiving low dose amino acids had better-preserved renal function than those receiving high dose amino acids. However, the type of solution infused did not affect recovery of renal function.