The effects of administration of Lactobacillus gasseri SBT0270 on serum lipids and bile acids, faecal bile acids and microflora were estimated in hypercholesterolemic rats. An effective dose of strain SBT0270 to exert its hypocholesterolemic effect was 109 viable cells/d. The dose of 109 cells/d did not affect the faecal coliform counts, but the number of faecal lactobacilli in rats fed this dose was significantly higher than that in the control group observed at the end of feeding period. Hypocholesterolemic effect of Lb. gasseri SBT0270 was attributed to its ability to suppress the reabsorption of bile acids into the enterohepatic circulation and to enhance the excretion of acidic steroids in faeces of hypercholesterolemic rats.