Reactive oxygen species (ROS) has many biological roles. Apoptosis is also induced by ROS. In this study, we show the involvement of ROS on the PC12 cell apoptosis induced by various agents. The agents to induce apoptosis were: amyloid beta peptide, moxalactam, doxorubicin, daunorubicin, etoposide and cisplatin. Antioxidant used were: N-acetylcystein (NAC), ascorbic acid, alpha -tocopherol, epigallocatechin-3-gallate (EGCG) and curcumin. The degree of cell death was assayed with MTT assay. The apoptosis was alo confirmed with nuclear pattern of PI stained cells and DNA ladder. The ROS was checked by flurospectrometry of DCF in the cells. The LD50 inducing apoptosis were in the following order daunorubicin (3.2 microM), doxorubicin (19 microM), etoposide (22 microM), amyloid beta peptide (110 microM), cisplatin (118 microM) and moxalactam (1.1 mM). The apoptdic cell injury patterns of all agents were confirmed by PI staining and DNA fragmentation. Doxorubicin, daunorubicin, amyloid beta peptide and moxalactam increased ROS in the cells treated in 1 hr. NAC reduced the apoptosis and ROS induced by doxorubicin, daunorubicin, amyloid beta peptide and moxalactam. Ascorbic acid reduced the apoptosis induced by etoposide and moxalactam, while alpha-tocopherol reduced the apotosis induced by moxalactam only. EGCG and curcumin reduced the apoptosis induced by doxorubicin, daunorubicin, amyloid beta peptide and moxalactam. It is concluded that PC12 cell apoptosis by various agents is mediated by intracellular ROS and that it may effectively reduced by flavonoid antioxidants rather than by ascorbate and alpha-tocopherol.