This study was conducted to evaluate the effect of different feed additives (Probiotics, Prebiotics, Synbiotics, Organic
acids and Enzymes) on chicks' immunity (Antibody titer against Newcastle vaccine, differential leukocyte count, total
proteins, albumin and globulin value) and economic efficiency analysis by using production functions under summer
condition. Our results showed that, enzyme treated group recorded the highest value of white blood cells. Organic acids
treated group for Ross breed showed the highest value for lymphocyte percentage. Heterophils percentage value was the
highest for probiotics and synbiotics treated group. Concerning antibody titer to vaccination against Newcastle, we found
that all the experimental groups had a positive effect on antibody titer. Regarding, albumin value, it was the highest for
probiotic treated group, while globulin value for Cobb breed showed higher value for all treated groups in comparison to
control group except for probiotic treated group. Regarding the effect of these additives on body weight and total return,
we found positive relationship between feed additives and body weight and total return. On the basis of our results, it
would be concluded that probiotics, prebiotic, synbiotic, organic acids and enzymes had positive effect on immunity and
economic performance of broiler chicken.