A total of 480 day-old chicks (Cobbs) were randomly assigned to three treatments as follows: 1) aflatoxin-contaminated diets (control); 2) aflatoxin-contaminated diets + 0.2% bentonite-montmorillonite (BM); and 3) aflatoxin-contaminated diets + 0.4% BM. The starter and finisher diets contained 3.45 and 21.68 ppb of aflatoxin B1. Results showed that at 28 days of age, average body weight gain was not significantly different among treatments. Broilers fed diets with BM were more efficient in feed utilization at 28 days than those fed diets without BM. Birds in the control group were less immunoresponsive to Newcastle Disease vaccine than those given aflatoxin-contaminated diets with BM. BM was able to neutralize the immunosuppressive effect and hepatotoxic activity of aflatoxin; hence, birds fed aflatoxin-contaminated diets with 0.4% BM had normal liver and responded to ND vaccine with consistently high HI antibody titres.