Preparation of atomically smooth SrTiO3 substrates is a crucial step for fabricating various high-quality thin films. This step can be in situ accomplished by homoepitaxial growth of several unit cells of SrTiO3 on commercially available substrates using laser molecular-beam epitaxy. The atomic-level smoothness of as-treated substrates was verified by AFM image and well-defined intensity oscillation in reflection high-energy electron diffraction. This simple procedure can be applied to epitaxy of several kinds of oxide films. (C) 2003 Elsevier Science B.V. All rights reserved.