Background: To evaluate the protective effects of magnesium isoglycyrrhizinate on a mouse model of concanavalin A (ConA)-induced immunological liver injury. Materials and Methods: Forty-eight mice were randomly divided into a normal control group, a model group, three dose groups of magnesium isoglycyrrhizinate (12.5, 25, 50 mg/kg) and a dexamethasone group (2.5 mg/kg). Magnesium isoglycyrrhizinate was intraperitoneally injected for 5 consecutive days, and the model of immunological liver injury was established on the fifth day after caudal vein injection of ConA (20 mg/kg). Blood was collected to detect the activities of alanine transaminase (ALT) and aspartate transaminase (AST) as well as the levels of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). The levels of neopterin (NP) and malondialdehyde (MDA) and the activities of myeloperoxidase (MPO) and superoxide dismutase (SOD) in liver tissues were measured, and histopathological changes were observed. Results: The serum levels of ALT and AST in the model group increased. Hepatic lobules had necrotic foci and inflammatory cell infiltration. The plasma levels of TNF-α and IFN-γ increased. In liver tissues, the levels of NP, MDA and MPO rose, but that of SOD decreased. Magnesium isoglycyrrhizinate significantly attenuated the activities of ALT and AST (P<0.05). Histopathological staining showed that inflammation of the liver was relieved significantly. Magnesium isoglycyrrhizinate also decreased the levels of NP, MDA and MPO in liver tissues (P<0.05), raised that of SOD and reduced the plasma levels of TNF-α and IFN-γ (P<0.05). Conclusion: Magnesium isoglycyrrhizinate protected against ConA-induced immunological liver injury in mice, probably through immune regulation and antioxidation.