Abstract: This study was carried out to determine the effects of excess dietary Lysine (Lys) and Methionine (Met) on some blood parameters, cholesterol and fat content of carcass and the performance of broiler chicks. In a completely randomized design three hundred male Ross 308 broilers were allotted to five group, each of which included four replicates (15 birds per replicate). The groups received the same basal diet supplemented with Lys and Met (as TSAA) in 0, 10, 20, 30 or 40% more than NRC recommendation. The collected data were analyzed by SPSS software and Duncan’s test was used to compare the means on a value of p<0.05. The results indicated that the two highest levels of Lys and Met treatments (30 and 40%> NRC recommendation) led to significant increase in carcass efficiency, breast muscle yield, heart and liver weight and also plasma cholesterol (p<0.05) whereas Feed Conversion Ratio (FCR), crude fat contents of breast and thigh muscles and plasma triglyceride were the least in these two treatment groups (p<0.05). Addition Lys and Met 40% more than NRC tend to significant decrease in body weight gain but there was no significant effect of treatment on cholesterol content of the breast and thigh muscle and also thigh and leg yield. The finding of this experiment showed that increasing Lys and Met to diets of today’s broiler in excess of NRC recommendations can improve FCR, abdominal fat deposition, breast meat yield, fat content of the breast and thigh muscles and carcass efficiency and also results reported here support the hypothesis that it is possible to produce poultry meat with different fat content by supplementation excess Lys and Met to diet.