Despite state-of-the-art therapy, clinical outcome remains poor in myocardial infarction (MI) patients with reduced left ventricular (LV) function. Stem cell-mediated repair of the damaged heart is a promising new development in cardiovascular medicine. Embryonic stem cells and adult progenitor cells have been extensively studied for their capacity to improve LV function recovery in preclinical MI models but underlying mechanisms remain incompletely understood. Recent placebo-controlled, randomized bone marrow cell transfer trials in MI patients have shown mixed results with cell-mediated effects on global or regional LV function recovery of variable magnitude and duration. There is now growing consensus that the observed effects of bone marrow-(BM)-derived progenitor cell transfer, as applied in post-MI patients thus far, occur independently of cardiomyocyte formation. Subgroup and meta-analysis of currently available randomized and observational pilot trials have highlighted limitations of current cell-based cardiac repair and provided suggestions for future focused clinical trial design. However, the two most recently reported randomized clinical trials failed to confirm a significant biological effect. A better understanding of underlying molecular mechanisms and modalities of cell-based repair is therefore mandatory to facilitate translation of innovative cell-mediated therapies for functional recovery after MI in the years to come. Rapidly growing insights in the biology of cardiac resident cells and technological advances in generation of patient-specific induced pluripotent stem cells may hold great promise to accomplish cardio-myogenesis and directly restore contractile force generation capacity.