Gardenia jasminoides is a popular traditional herb used to treat inflammatory diseases including liver disorders. This study was performed to examine protective effect of G. jasminoides on galactosamine (GalN)-induced acute hepatitis. Rats were treated intraperitoneally with GalN (700 mg/kg). G. jasminoides (30, 100 and 300 mg/kg) was administered orally 48, 24, and 2 h before and 6 h after GalN injection. Serum ALT and AST activities were significantly increased after GalN injection, and these increases were attenuated by G. jasminoides. Histological studies showed that G. jasminoides inhibited hepatocellular necrosis with inflammatory cell infiltration. GalN decreased the serum levels of total cholesterol and this decrease was attenuated by G. jasminoides. Hepatic glutathione content was decreased and lipid peroxidation was increased after GalN treatment and these changes were attenuated by G. jasminoides. Furthermore, the level of tumor necrosis factor-${alpha}$ mRNA expression was significantly increased after GalN injection, and this increase was attenuated by G. jasminoides. The level of interleukin-10 mRNA expression was significantly increased after GalN injection, and this increase was augmented by G. jasminoides. Our results suggest that G. jasminoides ameliorates GalN-induced acute hepatitis and this protection is likely due to antioxidative activity and regulation of inflammatory mediators.