Abstract: AIM To explore the effects of superoxide dismutase (SOD) level on long-term ventricular remodeling in patients with acute ST segment elevation myocardial infarction (STEMI). METHODS Sixty-seven patients ［60 males and seven females, mean age (58±11) years］ suffering from STEMI for (9.1±2.5) h were included in our study. Clinical baseline data and related biochemical indexes consisting of SOD and hs-CRP were collected within 24 h of admission. All patients were followed-up with echocardiography for 1 year and according to the follow-up results they were divided into enlarged left ventricular group (left ventricular end diastolic diameter, LVEDD≥55 mm for males and LVEDD≥50 mm for females) and normal left ventricular group (LVED 55 mm for males and LVEDD 50 mm for females). RESULTS Plasma SOD levels in enlarged left ventricle group were significantly lower than in normal left ventricle group (P<0.01). Furthermore, SOD in plasma was negatively related to LVEDD in patients with STEMI using logistic regression model (B=-0.049, P<0.05). Plasma hs-CRP in enlarged left ventricle group was significantly higher than in normal left ventricle group (P<0.01). CONCLUSION Decrease in plasma SOD is associated with size of left ventricle, indicating that the SOD level is one major reason for poor prognosis in STEMI patients.