Abstract: The Chinese drug Hai-Chou-Chang-Shan (Clerodendron tnchotomum Thumb.) belongs to family Verbenaceae which has been used as a sedative and antihypertensive drug. From the aqueous extract of its leaves, we have succeeded in isolating three crystalline components. The component (Ⅰ) was obtained in light yellow needles, C₂₇H₂₆O₁₇·3(1/2)H₂O, m.p. 215℃ (decomp.), yield 0.5%. Its U.V. absorption showes λ_max 270, 341 mμ, I.R. spectrum v_CO 1660 cm^-1, v_COOH 1730 cm^-1. It gave positive reactions with ferric chloride, Mg+HCl, and ZrOCl₂. It is soluble in diluted solution of sodium bicarbonate and sodium hydroxide in yellow colour, slightly soluble in methanol, ethanol and 60% acetic acid but insoluble in ether and other organic solvents. From its physical and chemical properties, it has been shown to be a new flavonoid compound, and, therefore, it is named clerodendrin. On hydrolysis with hydrochloric acid, the clerodendrin gave an aglycone, light yellowish needle crystals and a sugar portion. The aglycone has a m.p. 347℃ (decomp.) and a triacetate, m.p. 182℃ was obtained. The aglycone was lastly identified as apigenin and no depression of melting point was observed when mixed with an authentic sample. By paper partition chromatography and colour test, it shows that the sugar part of clerodendrin is glucuronic acid. When clerodendrin was esterified with methanol, a dimethylester m.p. 170℃ was obtained, the clerodendrin, therefore, must carry two carboxyl groups. We also further determined the glucuronic acid quantitatively by acid hydrolysis, and two moles were found. In order to ascertain the position of glucuronic acid, the clerodendrin was methylated with dia2omethane then hydrolyzed a known compound, acacetin, was obtained. From the positive test of ZrOCl₂ which demonstrates that the 5-position in clerodendrin is free, so that it is conclusive that the glucuronic acid must link in the 7-position. Therefore, the structure of clerodendrin has been confirmed to be apigenin-7-diglucuronide. The component (Ⅱ) was obtained in colourless crystals, m.p. 221℃, sweet taste; its acetate melted at 215-216℃. All of these properties were comformed to mesoinositol and its acetate, and no depression of melting point was observed when both were mixed with authentic samples respectively. The component (Ⅲ) is an alkaloid. It was obtained in colourless needles, m.p. 235℃, and gave positively with most alkaloid reagent, but its yield was too low for detail investigation.