Current treatments for ischemic cardiomyopathy are aimed toward minimizing the deleterious consequences of diseased myocardium. The possibility of treating heart failure by generating new myocardium and vascular tissue has been an impetus toward recent stem cell research. Mesenchymal stem cells (MSC), also referred to as marrow stromal cells, differentiate into a wide variety of lineages, including myocardial and endothelial cells. The multi-lineage potential of MSCs, their ability to elude detection by the host immune system, and their relative ease of expansion in culture make MSCs a very promising source of stem cells for transplantation. In addition, emerging experimental results with MSCs offer novel mechanistic insights into cardiac regenerative therapy in general. Here we review the characterization of MSCs, animal and human trials studying MSCs in cardiomyogenesis and vasculogenesis in postinfarct myocardium, routes of delivery, and potential mechanisms of stem cell repair.