The current study is planned to investigate the effect of aflatoxin B1 (600ppb) and the ethanolic extract of Thyme (500ppm) in broiler chickens. 240 unsexed Ross broiler chicks were randomly allotted into 4 dietary treatments with three replicates and twenty chicks per replicates and reared in cage systems for 42 days. Results showed that the body weights of broilers fed aflatoxin were reduced significantly (P<0.05) and feed consumption and FCR were increased significantly (P<0.05). The inclusion of Thyme essence have showed an improved data and addition of Thyme essence to aflatoxin fed groups could partially alleviate the adverse effects of aflatoxin in the diet. The antibody titer values against Newcastle Disease, Infectious Bronchitis and Avian Influenza of broilers fed aflatoxin were significantly (P<0.05) increased and incorporation of 500ppm Thyme essence could partially restore the negative impact of aflatoxin in commercial broilers.