This paper reports an approach to the fabrication of uniform Au nanoparticles in ultrahigh vacuum. Au atoms are physically vaporized by electron beam evaporation, and their subsequent growths on the substrate surface are chemically controlled by a self-assembled organic monolayer. Atomic force microscopy and scanning electron microscopy results reveal that large quantities of uniform An nanoparticles are thus fabricated. The diameters of the as-grown Au nanoparticles are about 5-7 nm, and the particle densities are 1.3-1.5 x 10(12) cm(-2). X-ray photoelectron spectroscopy analysis confirms the chemical interactions between the top An nanoparticles and the organic sublayer, by which the fabrication is achieved. (c) 2005 Elsevier B.V. All rights reserved.