The aim of this study was conducted to evaluate the efficiency of formic acid supplementation as growth promoters in broiler chicken. The study was carried out utilizing 132 Cobb commercial broiler chicks which were randomly assigned into two groups one having three levels of formic acid and the other one as control.  Each level contained 2 replicates of 11 chicks each. Birds in tow groups were fed basal diet (starter and grower) whereas birds in formic acid treatment were received water with 0.5, 0.75 and 1% formic acid. Results revealed that the birds supplemented with formic acids had significantly (p < 0.0001) lower body weight (BW) and higher body weight gains (BWG) at the levels of 0.75 and 1.0% at 35 days of age. Cumulative feed consumption was decreased (p < 0.0001) in the groups supplemented formic acids compared to control group which had high feed intake. Supplementation of formic acid improved (p < 0.0001) the feed conversion ratio (FCR) as compared with control group. Increased total fat and bursa weight were observed in groups fed formic acid while, the breast yield and dressed carcass were decreased.  Addition of formic acid at level of 1% to the diets of broiler chicken decreased (p < 0.001) the caecal viable and coliform counts compared to the un-supplemented group. The pH was decrease in formic acid treated group.