Abstract The effect of different levels of Met on performance and carcass quality of broilers was investigated. Based on a completely randomized design, three treatments including T1 (+10% NRC requirement of Met), T2 (NRC requirement of Met), and T3 (-10% NRC requirement of Met) were used. Feed intake (FI) , body weight (BW) and feed conversion ratio (FCR) were measured weekly. The effects of treatments on BW and FCR were not significant. Birds fed T1 had the highest FI among treatments, as the difference between T1 and T2 was significant. Significantly, carcass yield of T3 was lower than others. Birds fed control diet decreaes abdominal fat, significantly. The effects of treatments on other parameters (thigh, breast and liver percentages) were not significant. It can be concluded that diet formulation based on low Met level (-10% NRC) results in negative effects on broiler chickens