Background: The results of stem cell therapy trials in myocardial infarction using granulocytes – colony stimulating factor (G-CSF) are inconsistent among trials, and the long term outcome of G-CSF based stem cell therapy is remained unknown. We reported two year follow up results of two different strategies of G-CSF based stem cell therapy. Methods and Results: We compared outcomes of intra-coronary infusion of the mobilized peripheral blood stem cells (PBSCs) with G-CSF, mobilization alone with G-CSF and the control PCI alone in patients with myocardial infarction. At 2 years follow up evaluation, intra-coronary cell infusion improved LV systolic function and remodeling compared to baseline, but G-CSF alone did not. Cell infusion group showed better improvements of left ventricular ejection fraction (+6.2 짹 3.6% vs. -4.3 짹 10.1%; p=0.004) and end-systolic volume (-15.7 짹 13.0mL vs. +0.3 짹 16.7mL; p=0.075) compared to G-CSF alone at 6months follow up, and these trends were maintained till 2years follow up (p=0.094 and 0.046 respectively). Improvements in cell infusion group are not significantly better than that of control PCI alone group due to small sample size. Patients who received G-CSF administration showed a tendency of modest increase of binary restenosis (50% vs. 30%, p>0.05) and a greater late loss of minimal luminal diameter (1.41 짹 0.77mm vs. 1.09 짹 0.72mm; p>0.05) at 6 months follow up compared to the control group. Conclusions: Up to 2 years follow up, intra-coronary cell infusion with mobilized PBSCs by G-CSF is better than G-CSF alone. Efficacy of intra-coronary infusion of mobilized PBSCs should be evaluated in a large randomized controlled trial.