A Korean folk medicine, "DangYak (當藥)" has been used as a bitter stomachic in Korea. With regard to the botanical origin of this crude drug, it has been considered to be from Swertia species (Gentianaceae), but there was no pharmacognostical confirmation on it. In this study, the morphological and anatomical characteristics of three Swertia species growing in Korea, Swertia japonica Makino, S. pseudochinensis Hara and S. tetrapetala Pall. were compared to clarify the botanical origin of "DangYak". As a result, it was determined that the commercial "DangYak" from Korean traditional market was proved to be the whole plant body mixture of Swertia japonica and Swertia pseudochinensis.