Objective:To explore the protective effect of thyroid hormone supplement on the hepatocytes in a rat model of acute hepatic failure. Methods:Thirty-six SD rats were randomly distributed in three groups. In group-1(control group),the rats received only placebo. In group-2(AHF group),the rats received intraperitoneal injection of D-galactosamine and saline. In group-3(treatment group),the rats received intraperitoneal injection of triiodothyronine(T3)at a dose of 15 mg/kg in addition to D-galactosamine. Blood and liver samples were obtained in all animals for the determination of thyroid and hepatic function and assessment of hepatic injuries. Results:T3 was subnormal in rat model of acute hepatic failure. There were less hepatocyte injuries and lower mortality in the treatment group as compared to the AHF group(P < 0.05). Conclusion:A rat model of acute hepatic failure has euthyroid sick syndrome. Thyroid hormone supplement may improve the prognosis and have significant hepatocyte protection in this animal model of acute hepatic failure.