The fruits of Cornus officinalis have been used in traditional Oriental medicine for treatment of inner ear diseases, such as tinnitus and hearing loss. In the present study, we showed that the ursolic acid obtained from Corni fructus protected HEI-OC1 auditory cells from hydrogen peroxide cytotoxicity in a dose-dependent fashion. In addition, to investigate the protection mechanism of ursolic acid on hydrogen peroxide cytotoxicity toward HEI-OC1, we measured the effects of ursolic acid on lipid peroxidation and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) in hydrogen peroxide treated cells. Ursolic acid (0.05 - 2 ${mu}g/ml$) had protective effect against the hydrogen peroxide-induced HEI-OC1 cell damage and reduced lipid peroxidation in a dose-dependent manner. Pre-treatment with ursolic acid significantly attenuated the decrease in activities of CAT and GPX, but SOD activity was not affected by the ursolic acid or hydrogen peroxide. These results indicate that ursolic acid protects hydrogen peroxide-induced HEI-OC1 cell damage through inhibition of lipid peroxidation and induce the antioxidant enzymes CAT and GPX.