Objective: To study the changes of cardiac function and myocardial energy expenditure following treatment with granulocyte colony stimulating factor (G-CSF) in patients with heart failure after myocardial infarction. Methods: Thirty-eight patients with heart failure after myocardial infarction were randomized into G-CSF treatment group and control group. All the patients received conventional treatment (medication and interventional therapy), and the patients in treatment group were given additional G-CSF (600 mu g/day) for 7 consecutive days. The plasma level of brain-type natriuretic peptide (BNP) and the number of endothelial progenitor cells (EPC) in the peripheral blood were detected before and at 7 days and 4 months after the treatment. The cardiac functions (LVEF, FS, LVIDs, PWTs, EDV, SV, ET) was evaluated by ultrasonic imaging before and at 2 weeks and 4 months after the treatment. The MEE and circumferential end-systolic wall stress (cESS) were calculated by correlation formula. Results: The number of EPC was significantly higher in the treatment group than in the control group after the treatment especially at 7 days (P<0.01). In both groups, BNP level was lowered significantly after the treatment to recover the normal level (P<0.01). The cardiac functions and myocardial energy expenditure were improved in all the patients at 2 weeks and 4 months after the treatment, and the improvement was more obvious in the treatment group (P<0.05), especially in terms of the MEE and cESS was significantly lowered in the treatment group than in the control group after the treatment at 2 weeks (P<0.01), the LVEF and FS was significantly increased in the treatment group than in the control group after the treatment at 4 months (P<0.01). Conclusion: EPC mobilization by G-CSF can effectively improve the cardiac functions, lessen ventricular remodeling and reduce myocardial energy expenditure in patients with heart failure after myocardial infarction.