Prior studies suggest that endomyocardial implantation of autologous bone marrow (BM) mononuclear cell therapy improves symptoms and left ventricular (LV) function in patients with refractory angina; however, the therapeutic efficacy in patients with ischemic cardiomyopathy is unclear. In a randomized, double-blind, placebo-controlled trial, 28 patients with advanced ischemic cardiomyopathy [New York Heart Association III-IV, LV ejection fraction (LVEF) <40 %] were assigned in 2:1 ratio to receive endomyocardial injection of BM cells (100 million, n = 19) or placebo (n = 9), guided by electroanatomical mapping. After 6 months, there was no significant difference between the two groups in LV ejection fraction (LVEF) and LV end-systolic volume (LVESV), LV infarct volume, and LV peri-infarct ischemic volume as determined by cardiac magnetic resonance imaging or exercise capacity. In conclusion, endomyocardial implantation of autologous BM mononuclear cells did not improve LV function or remodeling in patients with advanced ischemic cardiomyopathy.