The study aims to investigate the effects of yeast glucomannan (GM) (Mycosorb (R), Altech) on performance, biochemical parameters and organ pathology in experimental aflatoxicosis in broiler chickens. A total of 120 one day old broiler chickens were assigned to 4 equal groups according to the dietary treatments: whereas the control birds (group C) received the basal diet, those from the group GM were only supplemented with 0.75 g/kg GM, those from the AF group were orally contaminated with 2 mg/kg total aflatoxins and those from the GM + AF group were exposed to aflatoxins and supplemented with GM for 21 days. Growth performance (body weights, weight gains). feed intake and feed efficiency were weekly assessed on all birds and at the end of the experiment, plasma biochemical parameters, visceral organ masses and conventional histopathology of liver and kidney were determined in 9 birds from each experimental group. The dietary aflatoxin contamination has significantly altered the growth performance (significant decreases in the final weight and in weight gains for the 3(rd) week and for the whole period), the feed intake mainly in the last week and the food efficiency, induced severe degenerative and necrotic lesions coupled to fibrosis in liver and kidney leading to significant changes in total plasma protein, total cholesterol, urea, creatinine and calcium concentrations, as well as in the AST (aspartate aminotransferase) and GGT (earnmaglutamyl transferase) activities. Nevertheless, the weight gains and feed efficiency were partially restored and the uraemia, the creatininemia and the plasma AST activity were significantly improved when aflatoxin contaminated birds were supplemented with GM despite the presence of liver and kidney damage similar to those observed in the AF group. These results demonstrate that a short duration (21 days) period is sufficient for inducing aflatoxicosis in broilers and that the yeast glucomannan supplementation at the dose of 0.75 g/kg may partially alleviated the deleterious effects but was insufficient for preventing tissue damage.