The chrysanthemum-like ZnO crystals have been prepared by the SDS assistant hydrothermal treatment method. The products were characterized by SEM, TEM, SAED, HRTEM, EDS and XRD. The results show that the as prepared ZnO crystals are chrysanthemum-like and composed of one-dimensional nanorods which have a single crystal lance-like hexagonal wurtzite structure. It is also shown that the nanorod constituents grow preferentially along the [0001] direction. A growth mechanism of the chrysanthemum-like ZnO crystals is suggested and explained in detail. (C) 2004 Elsevier B.V. All rights reserved.