Abstract: The cuticular patterns on leaf surfaces of 9 species of the genus Piper L. were studied with SEM (scanning electron microscope). It was found that they could be divided into two groups. The first group includes P. hancei Maxim., P. kadsura Ohwi, P. wallichi Hand-Mazz., P. hainanense Hemsl. and P. bambusaefolium Tseng. On the leaf surfaces of this group there are cuticles with warty protuberances. The second group includes P. austrosinense Tseng, P. arboricola C. DC., P. sarmentosum Roxb. and P. betle L., which is distinguished from the first group by its striated cuticles. Other distinguished characteristics of each of the above-mentioned species are described in detail with 4 plates of illustrations and summarized in an analytical key.