The field emission properties of ZnO are often strongly affected by their morphology and structure. The field emission properties of the 3D urchin-like ZnO nanostructures, which consisted of ZnO nanorods with sharp tips and were self-assembled via a simple hydrothermal route, are investigated in detail. The urchin-like ZnO nanostructures show a good field emission performance with a turn-on field of approximately 3.7 V microm(-1) (at 10 microA cm(-2)) and a threshold field of approximately 4.8 V microm(-1) (at 1 mA cm(-2)) and good stability (<4%, during a 250 min test). The field enhancement factor beta is estimated to be 1239. The field emission performance from the present ZnO forms can be comparable to the best value of ZnO nanostructures reported in the literature. It is demonstrated that the ZnO nanorod sharp tip morphology results in a good and stable field emission performance, which may find applications in field emitters.