The present study investigated the protective actions of telmisartan, an angiotensin II type 1 receptor blocker (ARBs), against the cell apoptosis induced by exposure to hydrogen peroxide (HO) in differentiated PC12 cells. Preincubation of PC12 cells with telmisartan prevented HO-induced cytotoxicity as indicated by increased MTT (3,(4,5-dimethylthiazole-2-yl)2,5-diphenyl-tetrazolium bromide) reduction, decreased lactate dehydrogenase (LDH) release, and improved morphological changes. Hoechst 33,258 staining showed that telmisartan markedly reduced shrunken nuclei of the cells, and Western blot analysis indicated that telmisartan significantly attenuated caspase-3 activity, as indicated by decreased ratio of cleaved Caspase-3 to its precursor and increased ratio of Bcl-2/Bax. The present findings showed that telmisartan protected against cellular oxidative damages by inhibiting apoptotic response.