Arsenic is a trace element widely found in nature.It exists in several forms, including trivalent arsenic and is the most toxic.Arsenic trioxide (As2O3) is widespread in nature.It tends to accumulate in animals and humans and therefore has a potential for great harm.Cytokines play essential roles in the immune response and inflammation.Although the importance of cytokines in the responses to arsenic exposure has been demonstrated in many types of mammals, the function of these in poultry, especially in chickens, remains unclear.In this study, 72 one-day-old male Hy-line cocks were randomly divided into four groups including control group, low-As group,middle-As group and high-As group.They were fed either a commercial diet or an arsenic-supplement diet containing 7.5, 15, or 30 mg/kg As2O3 for 90 days.The livers were collected on days 30, 60, 90 of the experiment.The levels of Nuclear factor kappa B (NF-κB), TNF-α, IL-4, IL-6, IL-8, IL-12β and IL-1β mRNA in the livers of the chickens were detected using real-time PCR.NF-κB seemed to be a critical mediator in the inflammatory response.The results showed that mRNA expression levels of IL-6, IL-8, TNF-α and NF-κB tended to increase in the birds chronically treated with arsenic trioxide.However, the mRNA expression levels of IL-4, IL-12β and IL-1β were decreased in the experiment.These results demonstrated that arsenic toxicity affected the liver function of chickens in vivo by regulating the cytokines levels.