Effect of citrus pectin oligosaccharides produced by irradiation was studied on the ability to improve lipid metabolism and hypercholesterolemia in mice fed high cholesterol diets. A total of 35 mice were divided into 5 groups and fed the following diets for 6 weeks: normal diet (C), 0.5% cholesterol (CH), 0.5% cholesterol+5% non-irradiated pectin (P), 0.5% cholesterol+5% irradiated pectin at 20 kGy (PIR), and 0.5% cholesterol+5% irradiated at 20 kGy and dialyzed (PIR-F). CH group had significantly higher serum triglycerides, total cholesterol, and low density lipoprotein (LDL)-cholesterol contents than pectin oligosaccharide-treated groups (p<0.05). Triglycerides and total cholesterol contents was the lowest in C and PIR-F and followed by PIR and P group, and CH group had significantly higher LDL-cholesterol. Serum high density lipoprotein (HDL)-cholesterol content in C group was not different from that in CH and P groups, but lower than that of PIR and PIR-F groups. These results suggest that pectin oligosaccharides produced by irradiation can reduce the levels of serum triglyceride, total cholesterol, and LDL-cholesterol in the blood of mice fed high-cholesterol diets and therefore, irradiation can be used as a tool to produce functional oligosaccharides from citrus pectin.