Because of its atomic resolution, scanning tunnel microscopy (STM) was applied to the study of the surface topography, in air, of rayon-based carbon fibers (RCF) that were not previously studied. By a variety of larger scales, RCF exhibits some rugosities with "peaks" and "valleys." The surfaces are characterized by stripe-form crystallite stackings with the diameter of about 10 urn aligned at an angle between 45 and 60degrees to the fiber axis. A graphitelike structure was first observed on the surface of RCF examined at an atomic resolution scale. Distances be-tween two adjacent carbon atoms of RCF and that between the closest centers of hexagonal carbon rings were estimated. It was also concluded that the hexagonal structure of RCF is deformed graphene (graphitelike) compared with that of highly oriented pyrolytic graphite. (C) 2003 Wiley Periodicals, Inc.