We report the Rutherford backscattering spectroscopy/channeling studies of epitaxial grown Ag films on Si(100) substrates irradiated with fast ions (12C++,19F++,28Si++) in the energy range between 0.5 and 4 MeV at 200 and −150 °C. The quality of the Ag films is improved considerably by ion irradiation. Irradiation with 0.5 MeV28Si ions to 2×1016/cm2at 200 °C, for example, reduces the channeling minimum yield from 55% to 6% at the Ag surface. The improvement of crystalline quality is brought about by a decrease in mosaic spread in the Ag film. Also, it is found that the higher the crystallinity, the more radiation‐induced defects are produced. The mechanism involved in the irradiation‐induced improvement is discussed. ©1996 American Institute of Physics.