The aim of this study was to evaluate the effects of soyoligosaccharides on intestinal microflora transit time lipid profiles and immune responses. Forty-eight male rats of Sprague-Dawley strain were divided into six groups(SYS: soybean oil-sucrose SYO: soybean oil-oligo SES; esame oil-sucrose SEO:sesame oil-oligo BFS : beef tallow-sucrose BFO : beef tallow-oligo) soyoligo-groups(SYO, SEO, BEO) were fed the diet containing 5% soyoligosaccharides but control groups not fed them and all groups were fed 20% fats for 4 weeks. The number of fecal bifidobacteria tended to increase after soyoligosaccharides feeding. The significant increase was found in SEO group compared to SES in that of fecal bifidobacteria,. Stool wet weight dry fecal weight and stool water content were increased significantly in soyoligo-group(SYO, SEO, BFO) compared to control groups(SYS, SES, BFS) and gastrointestinal transit time(TT) tended to increase. Soyoligosaccharides lowered plasma cholesterol in SEO group significantly more than did other groups. soyoligo-groups(SYO, SEO, BFO) tended to decrease liver triglycerides compared to control groups. Plasma IgG concentration increased in beef tallow groups(BFS, BFO) than that in other dietary fat groups. Soyoligosaccharides and kinds of fats had effects on plasma C3 concentration and mitogenesis of the spleen cells. Soyoligosaccharides had no effects on plasma leptin and insulin concentration but kinds of fats did so that sesame groups were decreased significantly in plasma leptin concentration but increased significantly in plasma insulin concentration compared to other dietary fat groups. In conclusion dietary soyoligosaccharides changed the composition of the intestinal microflora beneficially with sesame oil and partially had effect on plasma and liver lipid profiles .(Korean J Nutrition 33(6) : 597∼612, 2000)