This study was conducted to clarify the effect of the gut microflora on the utilization of dietary diammonium citrate in the chick. Germ-free and conventional Single Comb White Leghorn chicks were given a basal diet, which contained adequate amounts of all essential amino acids but none of the nonessential amino acids as nitrogen sources, or a diammonium citrate-supplemented diet. Irrespective of presence or absence of the gut microflora, values for body weight gain, feed efficiency, and protein and energy utilization were improved by supplementing the basal diet with diammonium citrate. This suggests that the gut microflora are not required for the chick to utilize diammonium citrate.