The effect of kabosu (Citrus sphaerocarpa Hort .) administration on serum and liver lipid concentrations in rats was tested using lees prepared from fruits at different stages of ripening and with different extraction methods: GC, green fruits with centrifugal extraction; GB, green fruits with belt extraction; and YB, yellow fruits with belt extraction. Four weeks old male Wistar rats were fed for 28 days on 20% casein diets containing either 4% cellulose (control diet) or one type of kabosu lees (concentration of total dietary fiber adjusted to 4% in each diet). Rats administered kabosu lees showed significant decreases in liver lipids, particularly total lipids, triacylglycerols, and cholesterol, compared with those fed on the control diet. However, no significant differences in serum and liver lipid concentrations based on fruit ripening stage or extraction method were observed. Kabosu lees administration significantly increased fecal excretion of total lipids and lowered the apparent digestibility of lipids. Levels of fecal total bile acids increased in rats fed on kabosu lees compared with the control diet . These results suggest that kabosu lees decrease the concentration of liver lipids by inhibiting the absorption of lipids and promoting the excretion of bile acids.