Totally, one hundred and sixty 1-day-old Ross 308 broiler chicks were fed with a diet containing 0, 0.5, 1.0, and 2.0 mg of aflatoxin B 1 (AFB 1 )/kg of feed for 21 days. Body weight was lower for the AFB 1 -treated broilers than for the control group. At 14 and 21 DPF, the broilers fed with 2.0 mg of AFB 1 /kg of feed weighed significantly lower than those of the other groups (p<0.05). Relative liver weights increased significantly in a dose-dependent manner, and relative spleen weights were significantly high in the chicks fed with 2.0 mg of AFB 1 /kg of feed at 21 DPF (p<0.001). Biochemical analyses showed that total protein and albumin levels decreased significantly at 7 and 14 DPF for the chicks of the group fed with 2.0 of mg AFB 1 /kg of feed, compared with those fed with 0.5 and 1.0 mg of AFB 1 /kg of feed (p<0.05). AST and ALT levels increased significantly at 14 and 21 DPF (p<0.05), and the AST levels, particularly, increased dose-dependently (p<0.05). Histopathological analyses showed that the liver tissues of the AFB 1 -treated chicks showed significant lesions, including hemorrhage, hepatocyte necrosis, inflammatory cell infiltration, and fatty degeneration. The severity of both hepatocyte necrosis and inflammatory cell infiltration appeared to increase dose-and time-dependently. Similarly, hepatic fibrosis increased dosedependently (p<0.05). The results of this study could improve our understanding of parameters used for evaluating aflatoxicosis in poultry.