Ag-doped ZnO thin. films were prepared on glass substrates by radio frequency co-reactive magnetron sputtering technique. The effects of Ag-doping on the microstructure and optical properties of the ZnO thin. films were studied by X-ray diffraction (XRD) and UV-visible spectroscopy. The photoluminescence (PL) measurements at room temperature revealed an ultraviolet and a blue emission. The origin of these emissions was discussed. It was also demonstrated that the optical band edge shifted to a shorter wavelength. first as Ag is incorporated, and then to a longer wavelength with the increasing of Ag-doping concentration. The optical band gaps calculated based on the quantum confinement model are in good agreement with the experimental values. (C) 2008 Elsevier B. V. All rights reserved.