Background This study examined feasibility and safety of granulocyte colony-stimulating factor (G-CSF) treatment for patients with acute myocardial infarction (AMI). Methods Forty patients with AMI related with the left anterior descending coronary artery, who underwent successful percutaneous coronary intervention (PCI), were randomized into G-CSF group ( n =18) or Control group ( n =22). G-CSF treatment was started within 24 h after PCI. 99m Tc-tetrofosmin single-photon emission computed tomography (SPECT) was performed at 4 days and 6 months after AMI. SPECT data was analyzed for LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LV ejection fraction (LVEF) and myocardial perfusion. Results LVEF at 6 months was significantly better than that at 4 days in G-CSF group ( p =0.013), but not changed in Control group ( p =0.245). Although no significant difference was observed for LVEDV between the two groups, LVESV tended to be decreased only in G-CSF group. In G-CSF group, defect score (DS) was significantly decreased from 4 days to 6 months after AMI. Restenosis rate at 6 months after AMI was not significantly different between the two groups. Conclusions G-CSF treatment for patients with AMI was effective and did not have any clinical and angiographic adverse effects.