The water extract of Omija-tang(OMJT) has been traditionally used for treatment of ischemic heart and brain damage in oriental medicine. However, little is known about the mechanism by which the water extract of OMJT protects cells from such damage. Therefore, this study was conducted to investigate the protective mechanisms of OMJT on $H_2O_2$-induced toxicity in H9c2 cardiomyoblast cells. Treatment of $H_2O_2$ markedly induced death of H9c2 cardiomyoblast cells in a dose-dependent manner. The characteristics of $H_2O_2$-induced death of H9c2 showed apparent apoptotic features, such as DNA fragmentation. However, OMJT significantly reduced both $H_2O_2$-induced cell death and chromatin fragmentation. The decrease of Bcl-XL expression by $H_2O_2$ was inhibited by OMJT. In addition, the increase of Bcl-XS and Bax expression were also inhibited by OMJT. In particular, Fas expression, which is generally recognized as cell death inducing signal by Fas/FasL interaction, was markedly increased by $H_2O_2$ in a time-dependent manner, whereas this increase was completely prevented by OMJT. The combined treatment of OMJT and $H_2O_2$ in H9c2 cells also reduced activation of caspase-9 and caspase-3 like protease. Taken together, this study indicates that the protective effects of the water extract of OMJT against oxidative damage may be mediated by the modulation of BcI-XL/S and Bax expression by way of the regulation of mitochondrial membrane potential and caspase cascades.