We have investigated the effect of Bi on the homoepitaxial growth of Fe(1 0 0) by means of reflection high-energy electron diffraction (RHEED). It was clearly found that Bi induces 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 Bi layer thickness suggests that there exist optimum amount of Bi surfactant layer that induces smoother layer-by-layer growth. The surface segregation effect of Bi was studied by Auger electron spectroscopy. A strong surface segregation of Bi was found at the top of surface and Bi atoms acted as a surfactant by promoting the interlayer transport. (C) 2003 Elsevier B.V. All rights reserved.