”Thang-kau-tin”, a folk medicine of Taiwan, has been used as an insecticide, to stop itching and as remedy for fever, rheumatic arthritis, snake-bite, hepatitis and liver cirrhosis. To clarify the origin of ”Thang-kau-tin” on Taiwan market, the pharmacognostical study was made. By means of a thorough investigation and employing anatomical studies, it has been demonstrated that the origin of ”Thang-kautin” on Taiwan market is derived from the following species: (1) the stem or the mixture of stem and root of Mallotus repandus (Willd) Muell.-Arg. (2) the stem of Bauhinia championii (Benth.) Benth. (3) the stem with hooks of Uncaria hirsuta Haviland and (4) the stem with hooks of U. rhynchophylla (Miq.) Jacks.