Abstract: 1.Chin-pi is used as a remedy for bacillary dysentary in Chinese medicine. As the name has long been applied to different drug plants in different districts, much confusion has been arisen about the genuine origin of this drug.In view of the great importance of Chin-pi in medicine it was deemed desirable to undertake detailed morphological and histological studies. 2. Morphological and histological studies have been carefully made on the barks of two species, namely: (1) Fraxinus rhynchophylla Hance.,(2)Juglans mandshurica Maxim. which are commonly sold under the same name "Chin-pi" in the market. 3. Flourescent analysis and microchemical tests for tannins, glycosides, and starch have been carried out. 4. The distinguishcd pharmacognostical characteristics of Fraximus rhynchophylla Hance. and Juglans mandshurica Maxim. are given in this paper and those of Fraxinus bungeana DC. and other species of Fraxinus Linn. will be published later.