Abstract: Eighty-four albino rats were divided into 7 groups. The average body weights in each group ranged 202--238 g. Hypertension was produced by kidney encapsulation. Starting from 1 day before or after the operation, the rats were given respectively the dried kernels of Zizyphus spinosus (20—30g/kg/dag, ad lib.), the flower of Chrysanthemum indicum (10 g/kg/day), Apium graveolens (ad lib.), dl-tetrahydropalmatine (20 mg/kg/day), hydrochlorothiazide (0.1 g/kg/day), and bretylium tosylate (10 mg/kg/day). Systolic pressure was measured by the tail plethysmographic method. The sum of the daily elevation of the systolic pressure (in mm Hg) in the 2nd postoperative week of the medicated group was compared with that of the control group. It was found that the kernels of Zizyphus spinosus inhibited the production of hypertension, while the other 5 drugs did not.