Abstract: A high performance liquid chromatographic method (HPLC)was developed for the determination of ergosterol in Cordyceps sinensis and Cordyceps black-bone chicken capsules. The sample was mixed with 0.5 ml of saturated KOH solution and 5 ml of ethanol, and refluxed for 1h. The saponified mixture was diluted with 5ml of 10% NaCl solution and extracted 3 times with 5 ml portions of cyclohexane. The cyclohexane extracts were purified by partition column and concentrated by adsorption column and then analysed by HPLC. The other conponents of the Cordyceps black- bone chicken capsules have no interference to the determination of ergosterol. The proposed method is rapid, precise, accurate and sensitive. The whole process can be done in 2h.