We have investigated the effect of Ag on the homoepitaxial growth of Fe(I 0 0) by means of reflection high-energy electron diffraction (RHEED). It was clearly found that Ag enhances layer-by-layer growth of Fe on Fe(1 0 0)-c(2 x 2)O reconstruction surface. The result of the dependence of the growth behavior as a function of Ag layer thickness suggests that there exists the most suitable amount of Ag surfactant layer that enhances the smoother layer-by-layer growth. (C) 2003 Elsevier B.V. All rights reserved.