The principal objective of this study was to assess the effects of chitosan oligosaccharide supplementation on the improvement of blood glucose, lipid components and enzyme activities in the serum of streptozotocin(STZ, 55 mg/kg B.W., I.P. injection)-induced hyperglycemic rats fed on experimental diets for 5 weeks. The concentrations of blood glucose, total cholesterol, atherosclerotic index, LDL, LDL-cholesterol, free cholesterol, cholesteryl ester ratio, triglycerides(TG) and phospholipids(PL) in serum were remarkably higher in the hyperglycemic group(group BSW) and STZ(I.P.)+chitosan oligosaccharide supplementation group(group ECW) than those in the control group(group BW, basal diet+water). However the concentrations of blood glucose, total cholesterol, atherosclerotic index, LDL, LDL-cholesterol, tree cholesterol, cholesteryl ester ratio, TG and PL in serum were lower in the ECW group than in the BSW group, whereas the ratio of HDL-cholesterol concentration to total cholesterol and HDL-cholesterol concentration in the ECW group were higher than in the BSW group. The activities of alkaline phosphatase(ALP) and aminotransferase(AST, ALT) in serum were lower in the ECW group than in the hyperglycemic BSW group. The results shown above suggested that chitosan oligosaccharide supplementation effectively improves blood glucose, lipid composition and enzyme activities in the sera of STZ-induced hyperglycemic rats.