The present study was performed to investigate the hepatoprotective and hypolipidaemic effects of a 27 kDa glycoprotein isolated from Gardenia jasminoides Ellis (GJE glycoprotein) in glucose/glucose oxidase (G/GO)-treated BNL CL.2 cells, as well as in CCl4, Triton WR-1339 and corn oil-treated mice. In G/GO-treated BNL CL.2 cells, the results showed that GJE glycoprotein has an inhibitory effect on G/GO-induced cytotoxicity and intracellular reactive oxygen species production. In addition, GJE glycoprotein has an anti-oxidant effect against the lipid peroxidation process in the Fe2+/ascorbic acid system. In CCl4 (1.0 mL/kg)-treated mice, pretreatment with GJE glycoprotein (80 mg/kg) blocked lactate dehydrogenase release and the formation of thiobarbituric acid-reactive substances. In addition, in these mice GJE resulted in increased nitric oxide production and the activation of anti-oxidant enzymes, accompanied by the inhibition of the cytotoxic-related signals hepatic cytochrome c, nuclear factor-kappaB and activator protein-1. In both Triton WR-1339 (400 mg/kg) and corn oil (1.0 g/kg)-treated mice, pretreatment with GJE glycoprotein (80 mg/kg) lowered the levels of plasma lipoproteins (triglyceride, total cholesterol and low-density lipoprotein). On the basis of these results, we assume that GJE glycoprotein can ameliorate liver function, because it has hepatoprotective and hypolipidaemic activities.