The purpose of this study was to investigate the influence of reducing crude protein of diets on growth performance, nitrogen content of excreta and the cost of feed and quail production. The experiment comprised of five 12.13 MJ metabolizable energy diets containing 240 (control), 230, 220, 210 and 200 g crude protein kg -1 supplemented with methionine, lysine and threonine amino acids. Reducing dietary crude protein from 240 to 200 g kg -1 had no effects on feed intake, weight gain and gain : intake ratio. In general protein consumption of the quails decreased and protein efficiency ratio increased with decreasing crude protein content (P<0.05). Decreasing dietary crude protein did not significantly affect dry matter of excreta. However, excreta nitrogen content of quail fed by diet 240 were higher than that of diet 210 and 200 (P<0.05). The cost of feed intake for each bird and cost of feed intake per 100 g weight gain not affected the amount of dietary CP. It is concluded that dietary crude protein could be reduced to 200 g kg 1 with meeting National Research Council recommendations for methionine, lysine and threonine amino acids, and metabolizable energy without adversely affecting the quail performance and costs, and decreasing excreta nitrogen content.