This experiment was conducted to investigate the effects of probiotics and prebiotics on growth performance, carcass yield, immune parameters, and microbial content in the commercial broiler. A total of 225 one-day-old chicks of the “Lohman Meat (Indian River)” strain having 42.66 ± 0.66 g average body weight were divided into 5 experimental groups with 3 replications of 15 chicks each. The treatments were T0= control (the basal diet), T1= antibiotic, T2= probiotic, T3= prebiotic and T4= probiotic + prebiotic. Weekly body weight, feed consumption, and feed conversion ratio (FCR) were recorded during the experimental period. Microbial counts were studied at the end of the experiment. The average live weight and body weight gain were significantly higher in T4 treatment compared to the other groups. Improved FCR was noticed in birds fed a combined addition of probiotics and prebiotics with the basal diet. Feeding broilers with probiotics and prebiotics have significant (P<0.05) effects on the dressing percentage, breast, thigh, back, liver, neck, heart, and gizzard while it appeared insignificant on the intestine, spleen, and bursa (P>0.05). Significant (P<0.05) difference was observed for immune parameters i.e. White blood cell (WBC), lymphocyte, and granulocyte among the treatment groups. Treatment groups found lower Escherichia coli and Salmonella numbers than the control group. Total profit per bird in group T4 was significantly higher (P<0.05) than in groups T0, T1, T2, and T3. From this study, it can be concluded that the combined use of commercial probiotics and prebiotics resulted in improved growth performance, carcass yields, and immunity in broiler chickens. Therefore, combined usage of the probiotic and prebiotic as antibiotic alternatives in broiler production can be recommended. پرونده مقاله