The amelioration of aflatoxicosis in broiler and Leghorn chickens was examined by feeding a hydrated, sodium calcium aluminosilicate (HSCAS) or activated charcoal. In three experiments, HSCAS or activated charcoal at a concentration of .5% of the total diet were incorporated into diets for broiler and Leghorn chicks containing either no added, purified aflatoxin B1 (AFB1), 7.5 mg of AFB1 per kg, or 5 mg of aflatoxin (AF) per kg (produced by Aspergillus parasiticus on rice). Compared to the controls, the AFB1 reduced BW gains at 0 to 3 wk by 21 to 38% in broilers; and the AF reduced BW gains at 0 to 4 wk in Leghorns by 20 percent. The HSCAS significantly diminished the growth-inhibitory effects of AFB1 or of AF on growing chicks by 50 to 67 percent. Feeding 5 mg of AF per kg of diet with or without charcoal to Leghorn chicks caused a significant increase in the relative weights of the liver, kidney, proventriculus, and gizzard as well as significant increases in activity of serum gamma glutamyltransferase; also, significant decreases in the relative bursa weights as well as the concentrations of serum total protein and albumin. With the exception of the relative bursa weights, the toxic effects caused by aflatoxin were prevented or were reduced by adding hydrated, sodium calcium aluminosilicate. These data suggest that HSCAS can modulate the toxicity of AFB1 and AF in the chicken; however, adding activated charcoal to the diet did not appear to have protective properties against the effects of aflatoxin B1 or of aflatoxin.