Abstract: AimTo study the therapeutic effects of n,n′-diacetyl-L-cystine (DiNAC) on immunological liver failure. MethodsSerum ALT, AST and T cell subsets in peripheral blood of the experimental animals during the trial period were analyzed by an automatic serum analyzer and a flow cytometer, respectively. The sectioned liver specimens were examined under a light microscope. And 24 h after the injection of Gal/LPS, the survival rate of rats was calculated. ResultsDiNAC (50, 200, 800 mg·kg^-1, ip) suppressed the elevation of serum levels of ALT and AST, markedly enhanced proliferation and differentiation of T cell subsets (CD4⁺, CD8⁺ and Th1, Th2), and improved all the histopathological features. In mice of fulminant hepatic failure (FHF), the survival time significantly prolonged and the survival rate increased 24 h after ip DiNAC. These effects were obviously dose-dependent. Conclusion DiNAC on mice with FHF has an inhibitory action which is related to immune mechanism.