It is controversial whether nitrogen can dope ZnO p-type or not. According to our first-principles calculations, no defects or defect complexes can result in p-type conductivity in ZnO. N-O and N-Zn-2O(i) have deep transition levels, while N-Zn-2V(Zn) has a high formation energy at the valence band maximum (VBM), rendering all of them unlikely to contribute to the p-type conductivity. Besides, N-Zn will heavily compensate the p-type doping of ZnO in O-rich conditions, while (N-2)(O) and (NO)(O) will do that in Zn-rich conditions. All these results raise serious questions about the feasibility of nitrogen as a p-type dopant. (C) 2012 Elsevier B.V. All rights reserved.