ABSTRACT - To examine antihypertensive components of Ganoderma lucidum in Korea, two kinds of fruiting bodies (J and K) were used for extraction with water and the extracts were purified by ethanol precipitation and dialysis. Three fractions, i.e., the aqueous total extract(A), the ethanol supernatant(B} and the purified precipitate(C), were compared for antihypertensive activity in anesthetized spontaneously hypertensive rats (SUR). Although fractions A and B showed the activity, fraction C did not. Particularly, fraction B of sample K produced 44.3% reduction in diastolic blood pressure and 30.6% reduction in heart rate after i.v. administration of a dose of 10 mg/kg. Direct effects of this fraction B to the heart were observed in the isolated blood perfused heart preparation of the dog. It induced positive chronotropic and inotropic responses dose-dependently in the case of sample J. In the case of sample K, marked chronotropic and inotropic effects on atrial muscle but not on ventricular muscle were induced. In both samples, coronary blood flow (CBF) was dose-relatedly increased.reased.