An initiator system for self-curing plastic material comprises a) at least one salt of a dialklylbarbituric acid and/or an alkylcycloalkylbarbituric acid and/or alkylarylbarbituric acid and/or a cycloalkylarylbarbituric acid that is insoluble in methacrylate monomers; b) at least one heavy metal salt that is insoluble in methacrylate monomers; c) at least one halogenide ion donor that is insoluble in methacrylate monomers; and d) at least one acid that is soluble in methacrylate monomers. The initiator system can be used for the preparation of paste/paste, paste/powder, paste/liquid, powder/liquid, and liquid/liquid combinations for the production of medical plastic material and dental materials. Additionally, a bone cement composition containing the initiator system is described.