ZnO microrods with various Ag doping levels were synthesized by a hydrothermal method. The effects of Ag on the ultraviolet (UV) emission properties of ZnO were investigated. The results demonstrate that the UV emission peak of ZnO centered at 391 nm has no shift after Ag doping, but the intensity of the UV emission is enhanced. It is very interesting that two peak values of the enhancement can be observed in the UV emission of ZnO with Ag doping levels of 0.05% and 0.20%, and the highest enhancement ratio of UV emission is 1.33, obtained from 0.20% Ag-ZnO. In this work, the enhancement of the UV emission of Ag-ZnO is regarded as a synergistic effect from the competition between the increase of the exciton concentration and the local field enhancement of metallic nanoparticles. In addition, the band gap values of ZnO slightly decreased with the increase of Ag doping level. (c) 2013 Elsevier B.V. All rights reserved.