The protective effects of Semen Hoveniae extract (SHE) from Hovenia dulcis Thunb. (Rhamnaceae) on acute alcohol-induced liver injury were investigated in vivo using mice as test models. In the present study, SHE (150, 300, 600 mg/kg/day) was given to mice by intragastric administration for 4 days. Mice were gavaged with 60% ethanol 10 mL/kg after the last dose of extract. Six hours after alcohol administration, liver injury was evaluated by biochemical examination. Lipid peroxidation and the activity of antioxidants were measured by spectrophotometric methods. In mice, administration of SHE significantly decreased the activities of alanine aminotransferase (ALT) and aspartate transaminase (AST) in serum. Administration of SHE also protected against alcohol-induced alcohol dehydrogenase (ADH) elevation in mice. Concurrently, there was an augmentation in the activities of antioxidant enzymes such as superoxide dismutase (SOD), glutathione S-transferase (GST), and glutathione (GSH), and it also facilitated alcohol metabolism. Acute toxicity tests showed that a single dose of oral SHE up to 22 g/kg did not result in any death or toxic side effects in mice during 14 days' observation. These results demonstrate that SHE could protect against acute alcohol-induced liver injury without any toxic side effects. Therefore, Semen Hoveniae has potential for the development of a clinically useful agent which could protect the liver from alcohol-induced injury.