The polymerization of methyl methacrylate (MMA) in bulk is initiated with FeCl(3.)6H(2)O or FeCl3/PPh3 at 90 degreesC without the addition any conventional radical initiator to the polymerization system. Although the elucidation of the detailed mechanism of the initiation needs further investigation, it is likely that redox-type reactions are involved in the generation of initiating species. Once the initiating radicals are produced, the polymerization proceeds via reverse atom-transfer radical polymerization (RATRP). It was found that the polymerization is controlled up to a molecular weight of 12900 at 92% conversion for the system using FeCl3.6H(2)O/PPh3. The chain extension experiment was carried out to confirm the controlled manner of the polymerization system. In both polymerization systems, polydispersity index and the initiator efficiency were found to be <1.4 and 0.6-0.9, respectively.