Abstract: A method for the determination of ranunculin in Pulsatilla chinensis and synthetic ranunculin by reversed phase HPLC using betamethasone as internal standard is described. The column employed was a 10μm LiChrosorb RP - 18 (230×4mm), the eluting solvent consisted of methanol-water(40: 10, V/V)and the effluent was monitored at 225nm.The advantages of thismethod are simple, rapid and accurate. The coefficients of variation are less than 1%.