Enzymatic parameters of in vitro metabolism of aflatoxin B1 (AFB1) in chicken, quail, turkey and duck are related to resistance to AFB1 toxic effects. Duck, a highly sensitive species, produce the higher ammount of AFB1-8,9-epoxide (AFBO) and AFB1 dihydrodiol (AFB1-dhd). AFBO is the bioactivated genotoxic form of AFB1 and can adduct guanine nucleotides in DNA. Spontaneous hydrolisis of AFBO produces AFB1, which in turns rearranges in a pH dependent manner to AFB1 dialdehyde. AFB1 dialdehyde adducts lysine in proteins and therefore leads to cytotoxicity. Enzymatic reduction of AFB1 dialdehyde occurs through aflatoxin B1 aldehyde reductase (AFAR) enzyme and products of this enzyme activity are AFB1 monoalcohol and AFB1 dialcohol (detoxifying products). It was observed that turkey (intermediate sensitive) and chicken (resistant species) possess the highest AFAR activity. In regards of aflatoxicol (reduced form of AFB1) production, it is related to more resistance species like chicken, quail, and turkey, as way to avoid AFB1 epoxidation, meaning that AFBO is produced at lower rates. In silico simulation demonstrated that duck species produce the higher amount of guanine and lysine adducts, in contrast to the other poultry species studied. This fact explains why duck is the only species that develop hepatocarcinoma and severe adverse effects. Apparently, AFB1 dialdehyde is eliminated as AFB1 dialcohol.