Abstract: Studies showed that the water extract of Coptis chinensis can lower serum glucose level in normal mice. Berberine, the major component of Coptis Chinensis, exhibited hypoglycemic effect in normal mice, alloxan diabetic mice, and spontaneously diabetic KK mice. Berberine can also antagonize the elevation of serum glucose level caused by intraperitoneal administration of glucose or adrenaline in normal mice. After administration of berberine for 15 days, the glucose tolerance of KK mice showed improvement. Furthermore, berberine was shown to lower serum cholesterol level of mice fed a high cholesterol diet and inhibit the platelet aggregation of rabbits in vitro.