The aim of the experiment was to investigate the efficacy of a smectite-based clay binder (Toxo-MX) in reducing the toxicological effects of aflatoxin B (AFB) in commercial broiler chickens. A total of 450 one-day old male broiler chickens were randomly allocated into three treatment groups with ten replicates of 15 birds each in a 42-day feeding experiment. The dietary treatments included a negative control (NC, a basal diet with no AFB and binder), a positive control (PC, a basal diet contaminated with 500 ppb of AFB) and a smectite-based mycotoxin binder(Toxo-MX, PC with smectite clay binder). AFB challenge resulted in 14 to 24% depression in growth performance, elevated levels of aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT), organ enlargement and immuno-suppression.As compared to PC, feeding of Toxo-MX improved the final weight (15%; < 0.0001), average daily gain (ADG) (15%; < 0.001) and feed efficiency of broilers (13%; < 0.0003) but did not have any effects on liver enzyme activities. Supplementation of smectite claysignificantly increased serum globulin levels and reduced the weight of the liver ( < 0.05) as compared to AFB-fed broiler chickens. The severity of lesions (inflammatory and degenerative changes) observed in the liver, kidney, heart, pancreas, and lymphoid organs in PC birds was reduced by feeding smectite clay. The immuno-suppression caused by AFB was moderately ameliorated in Toxo-MX groupby stimulating the production of antibodies against IBD at day 42 ( < 0.05). In conclusion, dietary supplementation of a smectite-based mycotoxin binder to the diet containing AFB improved growth performance, reduced toxicological effects in liver and improved humoral immune response in broilers, suggesting its protective effect against aflatoxicosis.