Certain indigestible oligosaccharides may benefit gastrointestinal tract via fermentation and proliferation of desirable bacterial species. The purose of this study was to elucidate the effect of selected oligosaccharides, such as fructooligosaccharides(FOS), soybean oliosaccharides(SOE), and highly concentrated branched oligosaccharides(HiBOS), on fecal micorflora proliferation, lipid concentration, lipid peroxide formation and antioxidant enzymes acitivies in plasma and liver of the rats. Thirty two male Sprague-Dawley rats were randomly assigned to one of four treatments ; 1) control diet(AIN-93G diet); 2) control diet +5% FOS ; 3) control diet + 5% SOE ; 4) control diet + 5% HiBOS. The duration of the study was 4 weeks. Fecal bifidobacteria concentration were significantly higher (p<0.05) in the HiBOS group compared with the control after 4 weeks of dietary treatment. FOS and SOE groups also had higher fecal bifidobacteria levels than control, but statistical significance was not found. The concentration of plasma total lipid was decreased by oligosaccharide consumption, especially in HiBOS group(p<0.05). The concentration of plasma total triglyceride was significantly lower in all of the oligosaccharide containing groups compared with the control(p<0.05). The plasma total cholesterol concentration tended to be lower in the oligosaccharide consuming groups than control. The concentrations of hepatic total lipid, triglyceride and total cholesterol were not affected by consumption of oligosaccharides. Thiobarbituric acid reactive substance(TBARS) concentrations and antioxidant enzyme activities in plasma and liver were not affected much by experimental diets. There results suggest that dietary oligosaccharides may be beneficial for increasing intestinal bifidobacteria and lowering plasma lipid levels.