Six experiments were conducted to define the amino acid and protein requirements of laying Japanese quail. In the initial experiments the diets contained 12% protein from a mixture of casein and soybean meal and were supplemented with essential amino acids and glutamic acid to promote optimum egg production. Later studies were conducted with corn-soybean meal diets. Results from varying the levels of essential amino acids led to the following estimates of amino acid requirements (as percent of the diet): arginine, 1.13; histidine, .38; isoleucine, .81; leucine, 1.28; lysine, .86; methionine plus cystine, .68; phenylalanine plus tyrosine, 1.25; threonine, .67; tryptophan, .17; and valine, .83. These amino acid requirements are correlated with the amino acid composition of quail eggs (r = .74). The total protein requirement of laying Japanese quail was found to be slightly greater than 16% of the diet when quail were fed diets based on either casein and soybean meal alone or casein and soybean meal supplemented with essential amino acids and glutamic acid. Based on the consumption of from 18 to 19 g of this diet per day the daily protein requirement was 2.88 to 3.08 g. Quail fed a methionine supplemented corn-soybean meal diet consumed up to 22 g of feed per day resulting in an estimated protein requirement of 3.52 g per day.