The effect of methionine supplementation on growth performance of 180 briolers type (Cobb) during growing period (1-21) days, fattening period (22- 42) days and the entire rearing period (1- 42) day, and carcass traits were examined. Three levels of methionine (0.10, 0.15 and 0.20%) were supplemented to corn-
soybean diet and compared with a normal diet (as control), for broiler feeding. Increasing methionine supplementation levels significantly improved weight gain and feed conversion efficiency, particularly at (0.15 and 0.20%) levels. Feed intakes were not significantly different among treatment groups. Carcass yield and breast yield increased at (0.15 and 0.20%) levels of methionine addition (P<0.05). Abdominal fat content and liver relative weights were not significantly different among the various treatments due to different methionine levels. Results of this experiment suggest that addition of methionine to corn-soybean diets had improved performance and carcass traits of broilers.