Carcasses and organs of 36 broiler chicks originating from an extensive fattening experiment with differing proportions of tryptophan (0.65 and 0.93 g/16 g N) to the neutral amino acids (15.2, 18.3 and 22.0 g/16 g N) in feed were analyzed for amino acid contents. Aside from the whole carcasses, a selected muscle (M. fibularis longus), liver, small intestine, and brain were prepared from the animals and analyzed. The organ weights differed according to the live-weights with the exception of the brain, where no group differences were measured. The patterns of amino acids of carcasses and organs remained nearly constant with differing amino acid supply. The only remarkable effect was the increase of the proportions of proline and hydroxyproline in the carcass protein from 6.4 to 7.4 and from 1.6 to 1.8%, respectively, with the higher tryptophan supply indicating increasing proportions of connective tissue. No relationship between weight gain and collagen content (calculated from hydroxyproline content) could be detected. The frequently supposed antagonism between tryptophan and the neutral amino acids, especially at the border of blood and brain, caused no reduction in tryptophan content of brain with increasing supply of neutral amino acids. There was, however, a significant depression of the development of the animals and the other inner organs.