In this study, 72 one-day-old, male, Avian race, broiler chicks were used. The birds were divided into 6 equal groups. While the first group was kept as a control, groups 2, 3, 4, 5 and 6 received for 45 d the feed containing 0.25% of sodium bentonite, 0.5% of sodium bentonite, 1 ppm of aflatoxin (AF) (approximately, 85% 131, 10% 132, 3% G, and 2% G(2)) 0.25% of sodium bentonite with 1 ppm of AF, and 0.5% of sodium bentonite with 1 ppm of AF, respectively. At the end of the experiment, the animals were sacrificed, blood was collected and plasma was separated. Plasma triiodothyronine (T-3), thyroxine (T-4), thyroid-stimulating hormone (TSH), testosterone, and growth hormone (GH) levels were measured. A significant decrease was detected in plasma T-3 and T-4 levels in groups 2, 3, 4, 5 and 6, and a significant increase in plasma testosterone level in groups 2, 4, 5 and 6, compared to the control group. FA and sodium bentonite, which were given alone, were found to be effective on T-3, T-4, and testosterone contents. In the case of their combination, there was no certain evidence that the adsorbent ameliorated the effects of AF. Therefore these parameters could not be used in in vivo studies of binding the FA with sodium bentonite in broiler chickens.