Peritoneal macrophages were harvested from both healthy mice and mice with diabetes induced by intravenous injection of streptozotocin. After incubation with normal plasma very low density lipoprotein (n-VLDL) from swine for 24 h, the content of triglyceride (TG) in macrophages from diabetic mice was higher than that in the controls, and it was the same with the concentration of free fatty acid (FFA) in medium. The basic concentration of cholesterol ester (ChE) in macrophages from diabetic mice was also higher than that of the controls. After incubation with beta-VLDL from hypercholesterolemic rabbit for 48 h, no alteration in ChE content was found in the cells. On the contrary, the content of ChE in the cells from the controls was accumulated by saturating. The levels of FFA in the medium of the diabetic group were still higher than those of the controls. These results demonstrated that the metabolic function of peritoneal macrophages in diabetic mice was altered. The uptake and degradation of n-VLDL and the endogenous cholesterol synthesis were increased, but the uptake of beta-VLDL was lower. In this paper, the possible mechanism and the relationship between atherosclerosis and diabetes are discussed.