1. The purpose of this study was to investigate the protective effect of alpha-lipoic acid (LA) on aflatoxin (AF) toxicosis in chicks. 2. Groups of 10 Ross PM3 chicks were given, for 21 d, no AF (C), 60 mg/kg/bwt of alpha-lipoic acid (LA), 150 ppb of aflatoxin (AF1), 150 ppb of aflatoxin plus 60 mg/kg/bwt of alpha-lipoic acid (AF1 + LA), 300 ppb of aflatoxin (AF2), and 300 ppb of aflatoxin plus 60 mg/kg/bwt of alpha-lipoic acid (AF2 + LA). Before the animals were killed, blood samples were drawn for haematological analysis, and then tissue samples were collected for histopathological investigation. Immunohistochemical staining was performed against inducible nitric oxide synthase (iNOS) and nitrotyrosine on liver samples. Apoptotic cell death in liver was assessed by in situ TUNEL assay. The malondialdehyde (MDA) and reduced glutathione (GSH) concentrations in liver and kidney were also determined. 3. Hydropic degeneration and occasional necrosis, bile duct hyperplasia and periportal fibrosis were observed in the livers of AF-treated groups. The severity of these changes was reduced in LA-supplemented AF groups. Occasionally, thymic cortical atrophy, lymphoid depletion in spleen and bursa of Fabricius, and degeneration in the kidney tubule epitheliums were detected in AF groups. The severity of these degenerative changes was slightly reduced in LA supplemented groups. 4. There was moderate to strong iNOS and nitrotyrosine immunoreactivity in the livers of AF groups, while decreased immunoreactivity was observed against both antibodies in the LA supplemented groups. Apoptotic cells were numerous in the AF groups, while greatly reduced in LA supplemented groups. 5. In the liver and kidney of AF-treated groups given 300 ppb of aflatoxin, MDA concentrations were increased as GSH decreased, compared to the control group. LA supplementation of AF-treated birds improved the results compared to the AF only groups, however a statistical difference was observed only in liver tissues between AF2 + LA and AF2 groups. Haematological variables showed no differences among the groups. 6. In conclusion, supplementation of feed with the antioxidant LA, might ameliorate the degenerative effects caused by aflatoxin due to lipid peroxidation.