Abstract: Chrysanthemum indicum is effective in lowering blood pressure. Extraction with hot ethanol yielded an active fraction, HC-1. In anesthetized cats, intraduodenal injetions of 50—100 mg/kg of HC-1 produced an average "% of hypotensive areas" in 2 hours varying from -19% to -22%. Four normotensive dogs were fed 50, 100, 130 and 150 mg/kg resp., and the diastolic pressure dropped 0, 24, 8 and 36 mm Hg resp. The hypotensive action was slow and lasted more than 2 hours. Three renal hypertensive dogs were fed daily 100 mg/kg in the first 2 weeks, and 200 mg/kg for the 3rd week. Weekly tests on EKG, serum BSP retention, and blood NPN revealed no serious alterations. In two of them the blood pressure was brought down significantly. Daily feeding of 300 mg/kg to one healthy dog for 3 weeks brought forth no grave reactions except vomiting at times. HC-1 is marked with (a) high yield, (b) low toxicity, (c) mild action, and (d) certain hypotensive effects in anesthetized and unanesthetized animals. So it may be recommended to clinical trial.