Background: Stem cell factor (SCF) plays a role in the regulation of hematopoietic stem cells (HSCs) in the stem cell niche in bone marrow. SCF has been shown to increase the survival of HSCs in vitro and contribute to the self renewal and maintenance of HSCs in-vivo. The aim of this study was to elucidate that the plasma levels of SCF in patients with acute ST elevation myocardial infarction (STEMI) and non-STEMI could be correlated with the traditional coronary heart disease risk factors and left ventricular ejection fraction. Methods and Results: A total of 73 patients (29 STEMI, 33 NSTEMI, and 11 control patients) who were admitted and underwent percutaneous coronary intervention from December 2009 to November 2010 were recruited. The presence of STEMI and NSTEMI were determined as standard methods and control group was determined by chest pain within the preceding 72 hours with or without ST–T-wave changes and negative cardiac biochemical markers (creatine kinase-myocardial band or troponin-I). Peripheral blood samples were obtained at each time points, before (basal level) and 3~4 days after stenting. SCF level was measured by ELISA kit (R&D system). The basal SCF levels in STEMI patients were lower than in NSTEMI patients (466.1 짹 121.9 vs. 652.5 짹 297.1 pg/ml, p < 0.05) and in control patients (656.8 짹 124.2 pg/ml, p < 0.01). After stenting blood sample time interval was 89.5짹43.4 hours in NSTEMI and 78.3짹30.8 hours in STEMI. SCF levels after stenting in NSTEMI patients were higher than in control patients (894.2 짹 329.2 pg/ml vs. 656.8 짹 124.2 pg/ml, p <0.05). However, no difference was observed in STEMI patients with control group. ∆SCF before and after stenting was 270.6 짹 135.6 in STEMI and 241.7 짹 129.1 pg/ml in NSTEMI patients. At subgroup analysis, STEMI patients were divided according to the basal SCF level (500 pg/ml). In STEMI patients less than 500 pg/ml SCF level, their basal levels were negatively correlated with left ventricular ejection fraction at six month echocardiography (r=-0.843, p <0.01). Conclusion: SCF plasma levels were increased after percutaneous coronary intervention and could be a predictive factor for left ventricular systolic function recovery in AMI patients.