Abstract: This experiment was conducted to evaluate the efficiency of nanozeolite against aflatoxicosis in broiler chickens. For this purpose, 336 male Ross 308 day old broiler chickens were allocated to 6 dietary treatments, including a control corn-soybean meal diet without Aflatoxin (AF) and Nanozeolite (NZ) and five diets contaminated with 500 ppb AF and containing 1 of 5 levels of zero, 0.25, 0.5, 0.75 and 1% Nanozeolite (AFNZ0, AFNZ0.25, AFNZ0.5, AFNZ0.75 and AFNZ1, respectively). Data were analyzed as a completely randomized design with 4 replications and 14 birds per repetition. The results showed that the lowest weight gain and feed intake and the highest feed conversion ratio were related to diet containing 500 ppb AF without NZ (AFNZ0 diet). The birds were fed AFNZ0 showed lower weight gain in 2nd, 3rd and 4th weeks in comparison with control diet (p<0.05). AF led to reduce feed intake and increase feed conversion ratio in 3rd week (p<0.05). No significant differences observed between control diet and contaminated diets containing different levels of NZ for body weight gain, feed intake and feed conversion ratio at all weeks. Serum total protein, cholesterol and triglyceride concentrations were significantly lower in AFNZ0 compared to control diet (p<0.05). There was no significant difference between dietary treatments for serum albumin. These findings confirm that at least 0.25% NZ is sufficient to reduce the toxicity of AF in broiler chickens.