p-type ZnO thin films have been realized by the N-Al co-doping method. Secondary ion mass spectroscopy demonstrated that the N incorporation was enhanced evidently by the presence of Al in ZnO. The lowest room-temperature resistivity was found to be 57.3 Omega cm with a Hall mobility of 0.43 cm(2)/V s and carrier concentration of 2.25 X 10(17) cm(-3) for the N-Al co-doped p-type ZnO film deposited on glass substrate. The results were much better than those for the N-doped p-type. ZnO. Moreover, the co-doped film possesses a good crystallinity with c-axis orientation and a high transmittance (90%) in the visible region. (C) 2004 American Institute Physics.