Silver/poly(methyl methacrylate) (PMMA) nanocomposites were synthesized in situ by thermally heating a solution of a silver n-propylcarbamate (Ag-PCB) complex and PMMA/MMA (1/9) in the presence of a radical initiator. Polymerization of the MMA monomers and reduction of the silver ions occurred simultaneously, leading to the formation of Ag/PMMA nanocomposites. The resulting Ag/PMMA nanocomposites were characterized by infrared spectroscopy (IR), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (TEM). TEM showed that the silver nanoparticles with diameters ranging from 5 to 30 nm were well dispersed in the PMMA matrix. Brownish transparent chips of the Ag/PMMA (0.1/99.9) nanocomposites with a particle size and distribution comparable to those of the Ag/PMMA nanocomposites were obtained by in situ reduction and radical polymerization using the silver nanocomposites with the composition, Ag/PMMA (4/96), as a master batch.