The polymerization of methyl methacrylate (MMA) initiated by the system lysozyme, copper(II) chloride, and water was carried out. The effect of the amount of each component on the conversion of MMA was studied. The polymerization proceeded through a radical mechanism. Urea, known to be a denaturing agent for protein, was able to promote the polymerization. On addition of urea, it was found that the following three reactions took place: (1) promotion of the polymerization of MMA with lysozyme, Cu(II) ion, and water by the unfolding of the third structure of lysozyme, (2) polymerization initiated by urea and Cu(II) ion, (3) polymerization initiated by the S-S bonds of lysozyme and urea.