Cell transplantation is a novel therapy for patients with postinfarction ventricular dysfunction and congestive heart failure. The potential of mesenchymal stem cells (MSCs) to be used in the injured myocardium is unlimited because of their ability to self-renew and differentiate into cardiomyocytes in vitro and in vivo. In addition, MSCs are easy to harvest and have a high proliferation capability. Finally, autologous MSCs can survive permanently and integrate with healthy host tissue to form new myocardium after implantation in vivo. We have used autologous cultured MSCs grafts for mouse and rat myocardial infarction in more than 500 cases. From these grafting experiments, it has been shown that cultured autologous MSCs grafting is a useful approach in the treatment of ischemic heart failure. This chapter offers a step-by-step guide for successful research on cultured MSCs for the treatment of myocardial infarction, as well as a set of techniques for evaluating postimplantation myocardial repair.