Stem cell transplantation (SCT) has emerged to be an appealing tool for repair medicine. In the treatment of ischemic heart diseases, SCT will be of great help because it is capable of replacing scar with new myocardial tissue. Among the many candidate cell lines for SCT, embryonic stem cells (ESCs) have their unique advantages. However, the controversy about the host immune attack and the transplanted ESCs or their derivatives transplanted into ischemic heart still existed. In this review, the immune properties of ESCs and ESC-derived cardiomyocytes and possible mechanisms were discussed; furthermore, the prevention strategies against potential immune responses were also identified.