Objective:To investigate the protective effect of thyroid hormone on hepatic ischemia-reperfusion injury and its possible mechanism in rat. Methods:The model of 70% hepatic ischemia-reperfusion was established in rat. Sixty-four healthy male SD rats were randomly divided into 4 groups. S:sham operation group;IR:ischemia-reperfusion group;IPC:ischemic preconditioning group;T3:thyroid hormone treatment group. After 6 h and 24 h of reperfusion,aspartate aminotransferase(AST),alanine aminotransferase (ALT) and tumor necrosis factor alpha (TNF-α) levels in the serum were measured;the superoxide dismutase (SOD) activity,levels of malondialdehyde(MDA) and glutathione (GSH) in the hepatic tissue were detected. Histologic changes was observed in HE staining,and the expression of NF-κB in liver cells was evaluated by immunohistochemistry. Results:After ischemia-reperfusion,compared with S group,IR group showed higher levels of ALT,AST,MDA,TNF-αand NF-κB and more obviously injury of liver tissue,but the activity of SOD and GSH decreased. After treatment of thyroid hormone and ischemic preconditioning,all above abnormal parameters were retrieved remarkably (P < 0.01).but there are no obvious difference between IPC group and T3 group (P > 0.05). Conclusion:Thyroid hormone,as well as ischemic preconditioning,has a protection against hepatic ischemia-reperfusion injury in rat. The mechanism of protection may be associated with its scavenging of radical,inhibition of lipid peroxidation,decrease of TNF-α level and suppression of NF-κB activation.