In order to study the effects of antibiotic, probiotic, prebiotic and enzyme in pelleted diet on performance and carcass characteristics of broiler chickens, an experiment was conducted as completely randomized design using 10 treatments, 4 replicates and 20 1-day-old male Arian broiler chickens in each. The experimental treatments were: 1) control, 2) diet supplemented with oxytetracycline (1 g/kg) for the first 21 days, 3) lincomycinspectinomycin (0.75 g/L) in drinking water up to 5 days old, 4) probiotic (1 g/kg), 5) prebiotic (1 g/kg), 6) multienzyme (0.5 g/kg), 7) lincomycin-spectinomycin in drinking water within first 5 days and then probiotic, 8) probiotic(1 g/kg) and prebiotic(1 g/kg), 9) probiotic(1 g/kg) and multi-enzyme (0.5 g/kg), and 10) prebiotic (1 g/kg) and multi-enzyme (0.5 g/kg). Body weight of broilers at any week of age was higher in experimental treatments than in the control (P<0.05). Broilers fed either diet supplemented with multi-enzyme or combination of multi-enzyme and probiotic or prebiotic had highest body weight among the treatments. Broilers received multi-enzyme in the diet had lower feed conversion ratio up to 35 day of age. Experimental diets had no effect on relative weights of carcass, wings, thigh, breast and back (P>0.05), although abdominal fat pad was affected (P<0.05). The most abdominal fat was corresponded to multi-enzyme and antibiotic groups. Feeding multienzyme in combination with probiotic and prebiotic increased body weight of broiler up to 21 day of age but after this age the combination had no more effect than multi-enzyme alone.