This work describes the pharmacological inhibition by KR 31378 and its acetyl metabolite, KR 31612, of the apoptotic cell death induced by H2O2 in the A7r5 cells. Exposure of A7r5 cells to H2O2 (0.5 mM) induced a concentration-dependent cytotoxicity in association with oligonucleosomal DNA fragmentation. H2O2-induced cell death was potently suppressed by KR 31378, KR 31612, α-tocopherol or trolox. Additionally, the apoptotic death of A7r5 cells (DNA ladders on electrophoresis) was also strongly suppressed by KR 31378 and KR 31612, but to a less degree by α-tocopherol and trolox. As a mechanistic study, incubation with H2O2 markedly showed a decreased Bcl-2 level and, in contrast, increased Bax protein and cytochrome C release, which were significantly and concentration-dependently reversed by KR 31378 and KR 31612 as well as by α-tocopherol and trolox. KR 31378 and α-tocopherol significantly reduced lipid peroxidation in accordance with reduced intracellular ROS and peroxyl radical. These results suggest that KR 31378 has a therapeutic potential against the apoptotic injury via mediation of anti- oxidative stress.