Abstract: Longdan, Radix Gentianae, is a well-known drug. It has been used for clearing up evil heat from liver and gallbladder and removing damp-heat from lower parts of the body in Chinese traditional medicine, and as a bitter stomachic in modern medicine.In order to provide means for the accurate identification of the commercial drugs derived from the following nine plants, viz. Gentiana manshurica Kitag., G. manshurica Kitag. ssp jiandeensis J. P. Luo et Z. C. Lou (ssp. nov.), G. scabra Bunge, G. triflora Pall., G. rigescens Franch., G. cephalantha Franch., G. suffrutescens J. P. Luo et Z. C. Lou, G. atuntsiensis W. W. Sm. and G. rhodantha Franch., morphological and histological studies of the drugs were undertaken. The results showed that all these drugs can be correctly identified by their mophological and histological characters, and keys for the morphological and histological identifications of the drugs are provided.Based on histological findings, the drugs Longdan derived from the above nine species may be divided into two types:A. Gentiana manshurica type--includes the drugs derived from Gentiana manshurica, G. manshurica ssp. jiandeensis, G. scabra and G. triflora. These drugs are characterized by the presence of exodermis, cortex, pith and scalariform vessels, by the absence of xylem fibres in the roots, and by the presence of lignified sclereids in their stems.B. Gentiana rigescens type--includes the drugs derived from Gentiana Tigescens, G. cephalantha, G. suffrutescens, G. atuntsiensis and G. rhodantha. These drugs are characterized by the presence of xylem fibres or phloem fibres, by the absence of exodermis and cortex in their roots as well as lignified sclereids in their stems.The above types divided according to the histological characters are in agreement with the result of taxonomical study.