Yam, Dioscorea batatas Decne (Dioscoreaceae) is a plant growing in Korea. Dioscoreae Rhizoma in the markets are classified into natural and cultural ones. These studies were conducted to investigate the differencies between natural and cultural Yams by characteristics of morphology, cell contents, chemical components and physical properties. More mucilage cells which contain calcium-oxalate raphides were contained in cultural Yam than natural Yam. However, the amount of crude protein, crude lipid and mucilage viscosity, swelling, gelatinization of polysaccharides were greater in natural Yam than the other. It is suggested that natural Yam is excellent as nutrition agent in quality and worthwhile as a resource of crude drugs.