One-day-old Avian breed broiler chicks were divided into 6 equal groups, consisting of 12 chicks in each. While group 1 was kept as a control groups 2, 3, 4, 5 and 6 were receiving for 45 d feed with addition of: sodium bentonite 2.5 g/kg; sodium bentonite 5.0 g/kg; aflatoxin 1 ppm (approximately 85%, 10%, 3% and 2% for AF B-1, B-2, G(1) and G,, respectively); sodium bentonite 2.5 g/kg + aflatoxin 1 ppm and sodium bentonite 5.0 g/kg + aflatoxin 1 ppm, respectively. At the end of the experiment, the chicks were sacrificed and their liver and kidneys were removed. The superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities and lipid peroxide (LPO) level were examined in both organs. According to the obtained data, the significant decreases in the GPx and CAT activities and significant increase in LPO level were detected in the liver tissues of groups 4, 5 and 6 compared to the control. The significant increase in LPO level in kidney tissues was found only in the groups 4, 5 and 6 compared to the control.