The influence of niceritrol on cholesterol in serum, liver and inner aorta of 115 rabbits was studied during a period where a cholesterol-enriched diet was given and during two succeeding periods after which cholesterol addition to the diet was discontinued. Niceritrol given together with cholesterol for 6 weeks reduced significantly the concentration of cholesterol in serum and liver, but not in the inner aorta. During 16 weeks decrease of serum cholesterol after discontinuation of cholesterol feeding no significant effect of niceritrol was observed on the decrease in serum and liver cholesterol or on the concentration of cholesterol in inner aorta. When serum cholesterol had normalized 16 weeks after discontinuation of cholesterol feeding, addition of niceritrol to the diet for the following 16 weeks did not significantly affect the concentration of cholesterol in liver and inner aorta. Animals in all groups were injected intravenously with an equal amount of [3H] cholesterol 3 weeks before discontinuing cholesterol feeding. Niceritrol did not significantly affect the amount of accumulated labelled cholesterol in inner aorta. The present results indicated that niceritrol had no significant effects on metabolism of cholesterol in inner aorta of the hypercholesterolemic and previously hypercholesterolemic rabbits.