Polymethylmethacrylate-silver (pMMA/Ag) nanocomposite is synthesized by irradiating the solution of silver ions in methylmethacrylate monomer by g-ray. In this method, polymerization of the methylmethacrylate monomer and the silver ion reduction occurred simultaneously. Optical properties of the PMMA/Ag solutions are investigated using UV-Vis spectroscopy. The structural characterizations of the PMMA/Ag nanocomposite are determined by FTIR spectroscopy XRD, and SEM measurements. The SEM image shows that the Ag nanoparticles disperse in the PMMA matrix with a relatively uniform distribution. The antibacterial studies show that the PMMA/Ag nanocomposite is antibacterial against E. coli, as a model for gram-negative bacteria.