Abstract: Clinopodium species (Fam. Labiatae) are widely distributed in China. Some of them are prescribed in Chinese traditional medicine or Chinese folk medicine for the purpose of hemostatic, antiphlogistic and antidotal effects. In this paper, comparative studies on morphology, anatomy and chemical constituents of Clinopodium chinense (Benth.) O. Ktze, C. polycephalum (Vaniot.) C. Y. Wu et Hsuan, C. confine (Hance) O. Ktze, C. gracile (Benth.) Matsum and C. repens (D. Don) Wall., as well as primary scanning electron microscope studies on their pollen grains, trichomes and stomata of their leaves are reported.It is taxonomically interesting that the stems and leaves of these 5 species show similar histological characters except for a few differences, such as in length and density of trichome, vein-islet number and stomatal index, etc.Chemical examination indicated that they all contain flavonoids, saponins, oligosaccharides, polysaccharides, phenolic compounds and essential oils.The chief distinguishing characters for identification between the 5 species of Clinopodium are tabulated.