ZnO ellipsoidal nanostructures were rapidly synthesized using a chemical synthesis method at 90 C without the assistance of aging procedure, calcination, sonication, microwave, laser or any organic additives. The effects of pH values and Zn2+ concentration on the morphologies of ZnO nanostructures were investigated. The instantaneous underdeveloped ZnO nanostructures were successfully obtained by using the electrophoretic deposition (EPD). Based on the experimental results, growth mechanism of ellipsoidal ZnO nanostructures was proposed. The ellipsoidal nanostructures are self-assembled by the oriented-attachment growth of primary nanoparticles, involving the end-to-end oriented-attachment along the major axis and the side-by-side oriented-attachment along the minor axis. Two half-ellipsoids of the ZnO nanostructures germinate in sequence. The UV-vis absorption and photoluminescence of the ellipsoidal nanostructures was also studied. This work presents a simple and ultra-fast route for large-scale fabrication of ZnO ellipsoidal nanostructures. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.