Objective To explore the effect of angiotensin converting enzyme inhibitor-Cilazapril on the oxidative stress of maintenance dialysis（MD）patients. Methods Thirty patients (hemodialysis 20, peritoneal dialysis 10) who had taken cilazapril 2.5 mg/d for 3 months were randomly selected. Their blood samples were taken pre and post the course. Blood MDA (malondialdehyde), AOPP (advanced oxidation protein product) and TAOC (total antioxidant capacity) were measured. Results After taken the cilazapril for three months, the patients blood pressure, hemoglobin, albumin, Kt/V, hs-CRP and TAOC did not change ( P>0.05), but the levels of MDA and AOPP in their blood decreased ( P<0.01). Conclusion Cilazapril can alleviate the oxidative stress of maintenance dialysis patients.