To test the cytoprotective effect of sophorae radix (SR) against hydrogen peroxide (H₂O₂)-induced cytotoxicity, we investigated the cell viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay in the presence of methylene chloride, n-butanol, ethyl acetate and water soluble fraction of SR water extracts in H9c2 cells. These results were obtained as followed; H₂O₂ decreased the cell viability of H9c2 cells in a dose dependent manner. Cells pretreated with SR water extracts were protected the H₂O₂-induced decrease of viability in H9c2 cells. Among organic solvents fractions of SR water extracts, ethyl acetate soluble fractions of SR protected the decrease of viability induced by H₂O₂ in H9c2 cells. These results suggest that ethyl acetate soluble fractions of SR water extracts is effective in the prevention of H₂O₂-induced cytotoxicity.