Résumé : A detailed procedure is presented for the determination of the amino acid composition of foods by chromatography of the hydrolysates on columns of Dowex-50 by the method of Moore and Stein. Nearly all of the common amino acids can be determined. The measurement of methionine, however, is complicated by partial oxidation of the amino acid to the sulfoxide during acid hydrolysis. A satisfactory chromatographic method for tryptophan has not been obtained as yet. Cross-reference is given to the auxiliary development of a Chromatographic method for the determination of cystine (in the presence of carbohydrate) as cysteic acid and to the utilization of these combined techniques in the analysis of several foods of importance in human and animal nutrition. © 1953.