This study was conducted to examine the effects of dietary xylooligosaccharides on hepatic HMG-CoA reductase activity and morphological exchange of liver in rats fed high fat diet. Sprague-Dawley male rats weighing 100 $pm$ 10 g were randomly divided into four groups, two normal diets and two high fat diets containing 1% cholesterol and 10% lard. Two normal diets were classified into a basal diet (normal group) and 10% xylooligosaccharide diet (NX group). The high fat diet groups were classified into a HF group without xylooligosaccharides diet and HFX group supplemented 10% xylooligosacchride diet. Experimental diets were fed ad libidum to the rats for 4 weeks and then they were sacrificed. The body weight of high fat diet (HF group) was increased more than that of normal group, but it was significantly decreased by xylooligosacchrides supplementation. The food intake was not significantly different among the all groups. The weight of liver, small intestine and cecum of all xylooligosaccharide supplemented groups were significantly heavier than those of normal and HF groups. The activity of hepatic HMG-CoA reductase, a rate limiting enzyme of cholesterol biosynthesis, in xylooligosaccharide supplemented groups was higher than that of HF group. Light micrographs revealed that the structures of hepatocytes in xylooligosaccharide supplemented groups were preserved well, compared to HF group. The xylooligosaccharide supplementation exerted a lipid-lowering action by decreasing cholesterol and triglycerides contents in hepatic tissue. In conclusion, the activity of hepatic HMG-CoA reductase and damage of liver in rats fed high fat diets were improved by dietary xylooligosaccharides.