These studies were conducted to investigate the feeding effect of dietary methionine and lysine on performance, meat quality, blood parameter and behavior of broiler chicks. A total of 720, 1-day-old broiler chicks (ross × ross) were randomly divided into Expt 1 and 2. Three hundred sixty were allotted to six treatments with four replication of 15 birds each for 35 days (prestarter: 0~7 days, starter: 8~21 days and glower: 22~35 days) and 42 days (prestarter: 0~11 days, starter: 12~24 days and glower: 25~42 days) in each experiment. Treatments were factorially designed by the two dietary meth (0.63, 0.57%; 0.57, 0.51%; 0.51, 0.46%) and three dietary lys (1.43, 1.36, 1.29%; 1,36, 1.29, 1.22%; 1.29, 1.22, 1.16%) for prestarting, starting and growing period. Weight gain, feed intake and feed conversion were measured according to the growth period. Blood and breast muscle were sampled at the end of both experiments and analyzed. Weight gain of the birds fed methionine supplementation was higher than supplementation of lysine treatments from prestarting to starting period, but was inferior to that of lys supplementation for growing period. Feed conversion showed the similar tendency to that of weight gain. However, the influence of dietary methionine supplementation tended to be higher than dietary lys supplementation on the performance of broile chicks at the end of experiments. Serum growth hormone (GH) and insulin like growth factor 1 (IGF-1) secretion were increased by dietary methionine and lysine supplementation (p<0.05) and improved performance of broiler chicks (p<0.05). Production and pH of breast meat increased in high lysine treatments (p<0.05). n-6 fatty acid and polyunsatureated fatty acid in breast meat increased in high methionine treatments (p<0.05). Furthermore, activity (walking and standing behaviors) increased of birds fed high mehtionine and lysine diets, while behavior of stress (preening and pecking behaviors) decreased in both those treatments (p<0.05). Thus, high dietary methionine and lysine improved performance by increasing weight gain, GH and IGF-1, improved meat quality, poultry welfare behaviors.