Abstract: The effects of dietary supplementation of a probiotic, Toxiban, Formycine and probiotic-Toxiban mixture on performance and immune response of broiler chicks were investigated. In a completely randomized design, one hundred fifty 14-days-old broiler chicks were assigned to 5 treatments with 5 replicates and 6 chicks in experimental unit. The experimental treatments were added to basal (starter and finisher) diets as follow: T (1): control group (C) that received starter and finisher diets, T (2): C plus 0.15 percent probiotic, T (3): C plus 0.1 percent Toxiban, T (4): C plus 0.1 percent Formycine and T (5): C plus mixture of 0.15 percent probiotic with 0.1 percent Toxiban. Additives except Toxiban, significantly (p<0.05) increased blood Newcastle antibody titer compared with the control group. Regarding Influenza antibody titer, there was significant differences between treatments except Formycine feeding. Only probiotic caused a significant (p<0.05) increased in blood Bronchitis antibody titer. Consumption of Formycine and probiotic+Toxiban mixture resulted in a significant decrease in blood Gamboro antibody titer (p<0.05). Chicks fed diets supplemented with Toxiban significantly (p<0.01) had higher body weight and better Feed Conversion Ratio (FCR) than other treatments. Results indicated that, consumption of Toxiban had the most positive effect on performance and probiotic alone or combination of probiotic and Toxiban had the best effect on blood antibody titers of broiler chicks.