A new type of flower-like ZnO nanostructure was prepared on a large scale through a very simple solvothermal method. The nanoflowers are assembled by many thin and uniform hexagonal-structured ZnO nanosheets, with a thickness of around 6 nm. The growth mechanism of the nanoflowers is discussed based on the reaction conditions. Room-temperature optical measurements reveal that such ZnO nanoflowers have very strong UV bandedge emission with a large Stokes shift and an asymmetrical band profile. This luminescence characteristic may be attributed to the anisotropic energy band structure of the quantum-confined ZnO nanosheets. (c) 2005 Elsevier B.V. All rights reserved.