To identify the animal origin of leather or parchment, samples of 2 or 3 square mm, are embedded in paraffin wax (melting point 54-56°C) after they have been softened. Then, horizontal and vertical sections are made. After staining, they are examined under a microscope with low magnification, x 40 or x 100. Identification is made possible by hair follicles which form the grain pattern. The microscopic examination of horizontal sections permits the observation of the follicular arrangement which is characteristic of animal species. An examination of cross sections provides additional information about the length of these follicles and the angle which they form with the skin surface. The compiling of a catalogue of ancient and modern leathers and parchments in various states of preservation has been undertaken. Each histological preparation produces a color photomicrograph which is classified. This preliminary work is necessary for the identification of an unknown material. Author's address: Centre de Recherches sur la Conservation des Docu-ments Graphiques, Muséum. National d'Histoire Naturelle, 36, Rue Geoffroy-St-Hilaire, Paris 5e, France.