The ability of dietary hydrated sodium calcium aluminosilicate (HSCAS), diatomite and activated charcoal (AC) in reducing the detrimental effects of aflatoxin B-1 (AFB(1)) in broiler diets was evaluated. Adsorbents were supplemented at 2.5 g/kg to the diets containing 0, 40 or 80 mu g AFB(1)/kg feed. One hundred and eighty Ross 308, day-old male broilers were assigned to 12 treatments for 42 days. AFB(1) at 80 mu g/kg feed resulted in a significantly lower body weight gain and feed efficiency than the control group. Addition of HSCAS in the diets significantly diminished the deleterious effects of dietary AFB(1). Aspartate amino transferase (AST), alanine amino transferase (ALT) activities and total protein concentration in the serum were altered significantly in the birds fed AFB, 80 mu g/kg feed. However, there were no significant differences between treatments in alkaline phosphatase (ALP) activity, and uric acid and creatinine concentrations in the serum. Liver weights of birds fed diets containing 80 mu g AFB(1)/kg feed were significantly higher than those of the control groups. Histological observations on livers from birds consuming AFB, at 80 mu g/kg feed showed a yellowish colour, portal leucocytic infiltration, congestion, multifocal fatty degeneration, and dysplasia of parenchymal cells with disorganization of the structure. The addition of HSCAS in the diets prevented an increase in the activity of AST and in the weight of livers and also prevented the histopathological changes induced by AFB(1). However, the addition of diatomite or AC in the diets failed to prevent the harmful effects of AFB(1). It was concluded that HSCAS is the most effective adsorbent to decrease the negative effects of AFB(1) in broiler chickens.