A series of experiments was conducted to determine how the essential amino acids in a corn-soybean diet should be proportioned for maximum growth during the second week posthatching. The diet contained 23% protein made up to 11.15% contributed by conventional ingredients and 11.85% protein in the form of free amino acids. Once the level of an amino acid giving maximum response was established, this level was used in all subsequent experiments. Most amino acids found to be required were lower than the levels of the corresponding amino acids in the starting diet formulated to meet the requirements of NRC (1977). The results indicated that growing broiler chicks require not more than 1.24% argine, 1.30% glycine plus serine, 0.80% isoleucine, 1.10% lysine, 0.40% methionine, 0.63% phenylalanine, 0.72% threonine, 0.17% tryptophan and 0.99% valine.