PS-B1 is a fermented product cultivated from soybean milk using lactic acid bacteria. We studied the effects of PS-B1 on the liver function and the lipid metabolism. The five testees took 50 mL⁄day of PS-B1 before going to bed for four weeks. Interestingly, the clinical examination values indicating the liver functions improved almost by drinking PS-B1 and the values of AST, ALP, and γ-GTP decresed greatly. The anti-oxidants contained in PS-B1 were suggested to suppress the release of liver-enzymes from hepatocytes by protecting hepatocytes from damages induced by the superoxide species. Moreover, the concentrations of total cholesterol, LDL-cholesterol, and triacylglycerol in blood were decreased and that of HDL-cholesterol increased. It was suggested that the feeding of PS-B1 in daily life might be useful to reduce the risk of the circulatory system disease such as the cerebrovascular disease and the coronary artery disease.