Previous clinical studies evaluating granulocyte-colony stimulating factor (G-CSF)-based stem-cell therapy showed inconsistent outcomes. We evaluated G-CSF-based stem-cell therapy in patients with acute myocardial infarction (AMI) and old myocardial infarction (OMI) in ‘Myocardial Regeneration and Angiogenesis in Myocardial Infarction with G-CSF and Intracoronary Stem Cell Infusion (MAGIC Cell)’ trials. In MAGIC Cell-1 trial, intracoronary infusion of mobilized stem cell by G-CSF is superior to G-CSF alone for improvement of left ventricular (LV) systolic function till 2 years follow-up. In MAGIC Cell-3-Drug eluting stent (DES) trial, cell infusion showed better improvement of LV systolic function and remodelling than control in AMI patients at 6 months follow-up. However, stem-cell therapy does not improve LV systolic function in OMI patients. G-CSF-based stem-cell therapy does not aggravate de novo progression of atherosclerosis while DES efficiently prevents G-CSF-based stem-cell-therapy-related restenosis. Longer-term follow-up is required to confirm prognostic impacts of stem-cell therapy in patients with myocardial infarction. Combination strategy with stem cell therapy with cytokines and genes should be introduced to enhance efficacy of current stem-cell therapy.