Eight severely burned patients received 10 grams twice a day of enterally administered ornithine alpha-ketoglutarate. Variations in their plasma and urinary amino acid levels were compared with those from six severely burned control patients. The study covered the period from the fourth day to the twenty-eighth day after injury. Essential differences between the two groups were that plasma ornithine and proline increased until day 13 in the treated group, plasma phenylalanine levels were higher in the control group except on day 13, the peak, on the twenty-first day, in plasma concentrations of valine, leucine, isoleucine, tyrosine, lysine, proline, and ornithine, in the control group was not found in treated subjects, and urinary amino acids were lower on day 28 in the treated group. These results suggest that ornithine alpha-ketoglutarate administration lowered protein catabolism after injury, probably through a process mediated by increased secretion of insulin and human growth hormone.