Aim To examine the advanced oxidation protein products(AOPP) and malondialdehyde(MDA) in patients with acute coronary syndrome(ACS) and discuss the relationship between oxidative stress and the development of atherosclerosis(As). Methods Plasma were collected in 73 acute myocardial infarction(AMI) patients including 46 patients undergone selective percutaneous coronary intervention(PCI)and 27 patients undergone emergency PCI,49 unstable angina pectoris(UAP) patients and 21 non-coronary artery disease(non-CAD) patients.All cases were undergone coronary angiography(CAG).Plasma were collected immediately,post-24 hours and post48 hours after patients were recruited.AOPP were determined by measurements of optical density(OD) via spectrophotometry,and MDA was measured with TBA methods. Results Compared with normal group(without CAD),plasma AOPP were significantly higher in AMI(selective PCI) and UAP patients(p<0.05).Significant difference also existed between selective PCI group and emergency PCI group in AMI patients (p<0.01).AOPP levels of UAP patients were significantly decreased after 48 hours(p<0.05);Pearson correlation analysis showed that AOPP was positively correlated to low density lipoprotein cholesterol(LDLC) in AMI patients(p<0.01).Compared with normal group(without CAD),plasma MDA were significantly higher in all AMI patients(p<0.05). Conclusions Oxidative stress may be an important step in development of ACS.AOPP and MDA may be as good markers in ACS patients.