Silver nanoclusters in poly(methyl methacrylate) (Ag/PMMA) were prepared by bulk polymerization of methyl methacrylate with radical initiators in the presence of silver(I) trifluoroacetate (AgTfa), followed by a period of heating. To compare the influence of the type of radical initiator on the formation of Ag nanoclusters, 2,2＇-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) were chosen as initiators. On the basis of the characterization of the solid sols of Ag/PMMA thus prepared, it was revealed by visible spectroscopy and TEM that the size of Ag nanoparticles increases with increasing initial concentration of AIBN and decreases with increasing initial concentration of BPO.