The aim of this study was to evaluate pharmacological properties of ethanol extracted from Mahonia oiwakensis Hayata stems (MOS(EtOH)). The pharmacological properties included antioxidant, analgesic, anti-inflammatory and hepatoprotective effects. The protoberberine alkaloid content of the MOS(EtOH) was analyzed by high-performance liquid chromatography (HPLC). The results revealed that three alkaloids, berberine, palmatine and jatrorrhizine, could be identified. Moreover, the MOS(EtOH) exhibited antioxidative activity using the DPPH assay (IC(50), 0.743 mg/mL). The DPPH radical scavenging activity of MOS(EtOH) was five times higher that that of vitamin C. MOS(EtOH) was also found to inhibit pain induced by acetic acid, formalin, and carrageenan inflammation. Treatment with MOS(EtOH) (100 and 500 mg/kg) or silymarin (200 mg/kg) decreased the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels compared with the CCl(4)-treated group. Histological evaluation showed that MOS(EtOH) reduced the degree of liver injury, including vacuolization, inflammation and necrosis of hepatocytes. The anti-inflammatory and hepatoprotective effect of MOS(EtOH) were found to be related to the modulation of antioxidant enzyme activity in the liver and decreases in malondialdehyde (MDA) level and nitric oxide (NO) contents. Our findings suggest that MOS(EtOH) has analgesic, anti-inflammatory and hepatoprotective effects. These effects support the use of MOS(EtOH) for relieving pain and inflammation in folk medicine.