Abstract: Objective　To explore the significance of plasma oxidized modified low-density lipoprotein (ox-LDL) in diabetes mellitus(DM) with atherosclerosis.Methods　The levels of plasma ox-LDL were measured by enzyme-link immunoabsorbent assay(ELISA) in 90 patients with DM and 30 controls.Results　The plasma ox-LDL level in patients with DM was significantly higher than that in normal controls. Type two DM patients showed higher ox-LDL level than type one DM patients.Higher ox-LDL levels could be found in patients with vascular complications and the patients with longer clinical course.Plasma ox-LDL was correlated with fast blood-sugar in DM patients.Conclusion　ox-LDL plays an important role in the pathogenesis of atherosclerosis in DM patients.Proper uses of antioxidants may prevent the DM patients from occurance of atherosclerotic complication or slow down the pathological process.