Guanidinoacetic acid is formed by the arginine and glycine that catalyzed by arginine:glycine amidinotransferase in kidney. In the liver, GAA is methylated by s-adenosyl methionine and converted to creatine, then deposited into muscle as energy supply. This meta-analysis was done by integrating 28 articles in various journals. Supplementation doses ranged from 0 to 8000 ppm/kg feed. The mixed model methodology was employed with level GAA and broiler strain as fixed effects and studies as random effects. The results showed that increasing GAA level improved average daily gain day 0-21 and reduced feed conversion ratio in day 0-35 (P<0.05). A higher of GAA also accompanied by decreasing relative liver weight (P<0.05). GAA supplementation did not affect to percentage of carcass (total, legs, breast, wings, drum, thigh) and other parameters such as abdominal fat, gizzard, heart, bursa, thymus and spleen (P>0.05). It was concluded that supplementation of GAA improved performance of broiler.