The Sprague-Dawley-strain rats were devided and classified into four groups: (1) the rats fed on the basal diets, (2) the rats fed on the basal diets containing 1% cholesterol, (3) the rats fed on the basal diets containing 16% spirulina, and (4) the rats fed on the basal diets containing 16% spirulina and 1% cholesterol. The results obtained were as follows. Elevation in total cholesterol, LDL+VLDL cholesterol, and phosholipids in serum caused by cholesterol feeding (Group 2) were reduced clearly by feeding (Group 4). Fall' in HDL cholesterol level caused by cholesterol feeding (Group 2) was reduced by feeding spirulina (Group 4). It was expected from these results that spirulina may prevent dietary hypercholesterolemia and arteriosclerosis. And, dietary hypercholesterolemia caused by cholesterol feeding was cured by spirulina feeding. The fatty liver caused by high-fat and high-cholesterol diets was also cured rapidly by feeding spirulina.