The amounts of diosgenin in Dioscorea nipponica Makino from different producing areas were determined by RP-HPLC and the best producing areas were found out. The amounts of diosgenin varied greatly in different areas. The amounts of diosgenin in Heilongjiang, Hebei, and inter-Mongolia were higher than that in other place. The amounts of diosgenin in Heilongjiang, which was considered to be the optimal producing area of diosgenin, was the highest (1.49%).