The contrast of biological samples in scanning electron microscopy (SEM) is very weak. To examine a biological specimen by SEM, many steps and/or special equipment are required to prepare the sample. Here, we describe a method using an Unstained biological sample Under a 40 nm carbon film to give a high contrast image, where the image is detected by the secondary electron (SE) signal at a low accelerating volt,e of 1.5 kV. Under these conditions, it is hard to detect a direct signal front a biological specimen. The age high contrast image is created by the SEs from the lower surface of the thin carbon film. Therefore, the damage to the sample from the electron beam is very low. Our method can be utilized to observe various biological samples of bacteria, viruses. and protein complexes. (C) 2008 Elsevier Inc. All rights reserved.