Cholesterol levels of 1% to 2% can be easily induced in rabbits by the simple expedient of adding cholesterol to their diet. Rabbits have little cholesterol in their diets normally, and their blood cholesterol levels are only 25 to 35 mg. % (in contrast to 100 to 250 mg. % for man). Since they do not have an effective mechanism for handling excess cholesterol, their metabolic systems may be overloaded with relative ease by adding sufficient cholesterol to their chow. Chickens may also be relatively easily overloaded with cholesterol by simple dietary means,1but animals which normally are exposed to considerable cholesterol in their food can handle excess cholesterol without developing hypercholesteremia unless some other factor is added. Thus, dogs may be rendered hypercholesteremic only if they are made hypothyroid,2,3which results in a decreased capacity for elimination of cholesterol. Rats may be made hypercholesteremic only if they are made