This study was conducted to evaluate effects of an organic acid at three levels of dietary electrolyte balances (DEB) on growth performance، acidity and gut microbial population of   broiler chickens. A total of 720 as-hatched  Ross 308 broilers were used in the study from day 1 old to 40 days of age. The experiment was carried out using a complete block design with factorial arrangement (2×3). Each dietary treatment were replicated 4 times. Experimental diets included 3 levels of DEB (200, 250 and 300 mEq/kg) with or without 0.4 % of the organic acid. Effects of dietary treatments were evaluated on performance criteria, carcass components, gut microbial population and pH of different sections of gastrointestinal tract. The results showed that feed intake of chickens fed  300 mEq DEB were higher than two other groups (200 and 250 mEq) and the effects were significant during finisher and entire periods (P<0.05). Dietary supplementation of organic acid also increased feed intake in all experimental periods (P<0.05). The average weight gain of chicks received diet with 300 meq/kg DEB was higher than other groups during the starter and grower period (P<0.05). Effect of organic acids on weight gain was significant during all stages of experiment (P<0.05). Gizzard weight of broilers fed diets containing 300 mEq DEB was higher, but the difference was significant only with 200 mEq DEB (P<0.05). Organic acids supplementation of dietary treatment had significant effect on femoral and back percentage (P<0.05). The main and interaction effects of dietary treatments on feed conversion ratio were not significant. The enterococci count decreased in 300 mEq DEB also a significant difference was observed between 300 mEq DEB and 200 mEq DEB treatment (P<0.05). The results showed that using organic acid could increases weight gain and feed intake of broilers without any change in microbial population of cecum or changing the pH of GI.