This study investigated the effects of soyoligosaccharide consumption on lipid profile of plasma, liver and feces and immune responses in Sprague-Dawley male rats. Sixty male Sprague-Dawley rats 4-wk-old were provided the soyo-ligosaccharide containing diets for 4 weeks (0, 100 g/kg diet); each of these diets was supplemented with either 70 or 200 g fat/kg diet, giving a total of 4 experimental groups. The effect of weight reduction was most significantly observed in the group fed low fat and soyoligosacchairde diet. The plasma total lipid and cholesterol contents were not changed by either fat proportion or soyoligosaccharide supplementation in the diets. Also the plasma triglyceride lowering effect by soyoligosaccharide was not observed in rats fed either low fat or high fat diet. However, the significant decrease in TG contents was found with rats fed high fat diets compared to the control/no soyoligosaccharide diet. Elevation of plasma LDL-cholesterol and reduction of HDL-cholesterol by feeding high fat diet was not altered by supplementing soyoligosaccharide. This was also applied to the liver lipid profiles. The significant increases in liver total lipid, trigly-cerides and cholesterol by high fat diet was not abolished by feeding soyoligosaccharide. However, the desirable effects of feeding soyoligosaccharide were found with total lipid and cholesterol excretion through feces in rats fed high fat diets. Immune organ weights and spleen cell proliferations did not affected by experimental diets. These results de-monstrated that soyoligosaccharide intakes increased the lipid output via feces, especially in rats fed the high fat diet, but more researches are needed on immune responses.