The objective of the work was to investigate the response of broiler chicks to supplementing guanidine acetic acid (GAA) in diets with different protein levels on performance and carcass characteristics. A total number of 360 one day old of male Hubbard broiler chicks were weighted and divided into sex dietary treatments of 60 chicks each with 6 replicates (10 chicks each), in 2 x 3 factorial design as follows: T₁ standard diets without feed additives (SD), T₂ SD (T₁ diets) + 0.06% (GAA) T₃ SD (T₁ diets) + 0.12% (GAA), T₄ Tested diets (-2% CP) without feed additives (TD), T₅ TD (T₄ diets) + 0.06% (GAA), T₆ TD (T_­4­ diets) + 0.12% (GAA). The results indicated that: -    Productive performance of broiler chicks including live body weight: Body weight gain, feed conversion ration, performance index, production efficiency factor, protein conversion ratio and energy conversion ratio were significantly affected by feed additives (GAA) and levels of crude protein at experimental period (1-35 days) of age. Feed intake recorded insignificant response due to experimental factors (feed additive or protein level). Carcass characteristics: Dietary treatments with different (GAA) levels (0, 0.06 and 0.12%) or different protein levels had no significant effect on most studied parameters. It may be concluded that broiler diets containing -2% crude protein + 1200 g GAA/ ton or standard diets + 600 g GAA/ton would be reason for achievement of maximum performance without adverse effect on carcass parameters