In this study, iron-mediated activator generated by electron transfer for atom transfer radical polymerization of methyl methacrylate was carried out using two different types of salts, acidic hydroxylamine hydrochloride and basic sodium bisulfite as the reducing agents, ethyl 2-bromoisobutyrate as an initiator, FeCl3 center dot 6H(2)O as a catalyst and triphenylphosphine (PPh3) as a ligand. The polymerization could be carried out in the presence of a limited amount of oxygen (air) and showed highly efficient catalyst activity. The living features were confirmed by the polymerization kinetics, analysis of chain end, and chain-extension experiment.