Abstract: Hypertensive disease is usually treated with "ying tonics" in Chinese medicine. In this paper the hypotensive action of 4 "ying tonics" were studied: Phellodendron sachalinense (Ps), Anemarrhena asphodeloides (Aa), Rehmannia glutinosa (Rg), and Ligustrum lucidum (LI). Rats were made hypertensive by (Ⅰ) burning of left adrenal cortex, (Ⅱ) orchiectomy, (Ⅲ) s.c. injection of testosterone propionate 5 mg/day to female rats for 16 days, and (Ⅳ) s.c. injection of stilbestrol 1—2 mg/day to male rats for 16 days. Blood pressure was measured by the tail plethysmographic method. Starting from the 6th week (but 5th week for model Ⅱ), the "ying tonics" were fed to the rats for 2 weeks. The daily dosages in terms of crude drugs were: 2 g/kg for Ps and Aa, 20 g/kg for Rg and LI, and 1 ml/rat for water as control. During the medication period, 4 "ying tonics" in model Ⅱ caused a drop of systolic pressure of more than 11 mm Hg. The systolic depression for Ps and Aa, moreover, amounted to 18 and 15mmHg resp., or -18% and -16% of hypotensive areas resp., which were highly significant. Thus Ps and Aa were deemed to be effective. Other models showed a depression of blood pressure all below 8 mm Hg. The % of hypotensive areas were non-significant. It is concluded that "ying tonics" did not show similar hypotensive effects in different models, nor even in the same model.