Two experiments were designed using 740 Japanese quail of one-day-old to study the effect of feeding low-protein diets supplemented with amino acids.  In Experiment 1, low-protein diets (22% and 20% CP) were supplemented with essential amino acids (Met, Lys, Thr, Iso-Leu, and Val) to meet the recommended requirements (NRC, 1994) and compared with high protein diets (26% and 24% CP, as control diets).  In Experiment 2, the same low protein diets used in Experiment 1 (22% and 20% CP) were used in this experiment but supplemented with only Met and Lys and compared with the 24% CP diet as a control diet.                 Results of experiment 1 indicated that live body weight, and body weight gain of quail chicks fed the 22% or 20% CP diet were significantly improved when these diets were supplemented with Met, Lys, and Thr and were not significantly different from those fed the high protein diets (24% or 26% CP). However, feed conversion was not significantly affected by reducing CP in the diets. Addition of Iso-Leu and Val did not give any further improvement in either body weight or feed conversion. Adding amino acids (Met., Lys., Thr. and Iso-leu.) to diets containing 20% CP gave the best economic efficiency (E.E) and the reverse was noticed with diets containing either 22% or 20% CP without Iso-leu supplementation. In Experiment 2, body weight and feed conversion of quail chicks fed diets containing 22% or 20% CP supplemented with Met and Lys were not significantly different from those obtained from with the 24% CP diet and increased E.E by 4% and 6%, respectively.                 It is concluded that performance of Japanese quail fed low-protein diets (22 or 20% CP) supplemented with amino acids was similar to that achieved with the high-protein diets (26 or 24% CP) and gave the best E.E.