Abstract: HPLC was applied to the determination of diosgenin in common yam rhizome. The sample was extracted with absolute alcohol and separated by using ZORBAX SB-C18 column as stationary phase and a mixture of methanol and water (80 to 20 by vol.) as mobile phase. The content of diosgenin was determined at the wavelength 210 nm. Linear relationship between values of peak area and mass of diosgenin was kept in the range of 10-150 ng, with detection limit (3S/N) of 2.5 ng. The proposed method was used in the analysis of sample of common yam rhizome, values of recovery found were in the range of 94.2%-104%, and RSD (n=6) found was 3.1%.