Abstract: Thevetoside, extracted from the seeds of Thevetia peruviana Merr, consists of three main cardiac glycosides, peruvoside, neriifolin, cerberin and two or three unknown minor glycosides.A colorimetric method was developed to determine the total glycoside content with picric acid-sodium hydroxide as reagent.The quantity of each. constituent in Thevetoside was determined by high performance liquid chromatagraphy. A 25 cm column of YWG-CH (C₁₈ chemically bonded stationary phase) was used with 70% methanol as the mobile phase. Five peaks were well seperated. The quantity was determined by peak height measurements.The analysis of crude drug was performed as follows: After fermantation, the glycosides in the defatted seeds were extracted with methanol. The methanol extract was purified by silica gel column with CHCl₃-MeOH (10:1) as eluant. After removal of the solvent, the residue was dissolved in appropriate amount of methanol and injected into the column.The contents of total glycoside and each constituent of some Thevetoside samples were determined. The results revealed that the proportion of the three main constituents was rather constant.The results obtained by chemical method and bioass(?)y were in good agreement.