Blocks of the kidney and other organs of the guinea pig fixed with glutaraldehyde and treated with tannic acid and osmium tetroxide could, without any coating, be observed in the scanning electron microscope. Undesirable charging effect was inconspicuous when accelerating voltage 5-25kV was used. A scanning image of the renal glomerulus was shown and the details of the method were described. The merit of this method is avoidance of the metal coating which obscures the details of the specimen surface.