It is known that soy protein has the hypolipidemic action on blood and liver. We investigated to clarify physiologically effective concentration of soymilk. Male Sprague-Dawley rats aged 7weeks were fed a control die（t AIN-93G, soy protein free）, or a test diet in which 10.78%（corresponding to soy protein 5%）or 21.55%（corresponding to soy protein 10%）of the diet was replaced with soymilk, respectively. The rats were fed the control diet or the test diet for 5weeks. The administration of soymilk significantly suppressed total cholesterol level in plasma and decreased liver lipid and visceral fat. These effects depended on the concentration of administrated soymilk. It was suggested that soymilk improved the lipid metabolism in rat. Moreover, it was found that the administration of amount of soymilk corresponding to more than 10% soy protein was necessary to obtain a significant physiological effect in a short period
