The effect of ginsenoside-Rb₂ purified from ginseng was investigated in streptozotocin-induced diabetic rats. The rats treated with ginsenoside-Rb₂ showed significant decreases in triglyceride, non-esterified fatty acid, and total cholesterol in the serum. A lipid-improving action in the serum was observed in rats with hyperlipemia. Furthermore, the lipolytic activity of lipoprotein lipase was stimulated with a concomitant decrease in the levels of triglyceride and very low density lipoprotein in the serum, while a repressive effect on hormone-sensitive lipase activity was observed. The accumulation of lipid in the adipose tissue was also observed. In addition to the hypolipemic effect, ginsenoside-Rb₂ exhibited a lowering action on the serum levels of 3-hydroxybutyrate and acetoacetate in streptozotocin-induced diabetic rats, indicating an improvement of diabetic ketoacidosis.