Abstract: Objective To investigate the long-term effect of artificial fiber complexes(AFC)on the intestinal structure in hyper cholesterolemic rats.Methods 60 healthy SD rats were fed with food rich in lipids and hyper cholesterolemic,and hypercholesterolemic rats animal models were established.Male and female weanling SD strain rats(80~100g)were divided into 5 groups,12 rats per group.As the negative and positive control groups,rats were fed either the normal dietor high-cholesterol diet respectively.The left groups were given one of the diets incorporated AFC at the different level of 5%,and 10% or 20%.The experiment lasted 3 months.At the end of the experiment,morphology of the small intestine were observed by light and electron microscope examination.Results Fecal weight could be raised in 20% of AFC group,but lowered in 5%,10% of AFC groups(P<0.05);the weights of small intestine wall in 20% AFC was significantly hig her than both of control groups,but 5%,10% of AFC could lower small intest ine wall weight(P<0.05).Except thickened muscle layer of small intestine were observed in 10% and 20% AFC group(P<0.05),the left small intestine structure was same as the normal control group.Widen villi and thickened muscle layer of small intestine were observed in 10% AFC group,microvilla becoming short and/or absent,mitochondria swelling,impairment of the integrity of the cristae were commonly observed in 20% AFC group.Conclusion Long-term intake of AFC at lower levels could be beneficial for small intestine's structure;on the other hand,long-term intake of AFC athigher levels could induce some morphological changes of intestine.