The effect of the ginseng root powder on avian hepatic cholesterol biosynthesis and serum lipoprotein cholesterol levels were examined. Lohman strain broiler females were fed for 4 weeks a corn-based diet (control) or an experimental diet in which 0.25% Korean ginseng was incorporated (treatment). B.-hydroxy-B-methylglutaryl-CoA) HMG-CoA reductase activity was significantly lower (P < 0.01) in the treatment group (47% of control activity). Ginseng treatment affected a lowering of the serum total cholesterol level (83% of control, (P < 0.05) and of serum low density lipoprotein cholesterol level (77% of control, P < 0.05). The mechanism of the hypocholesterolemic action of ginseng involves the suppression of cholesterol biosynthesis.