Cellular transplantation is emerging as a potential mechanism with which to augment myocyte number in diseased hearts. To date a number of cell types have been shown to successfully engraft into the myocardium, including fetal, neonatal, and embryonic stem cell-derived cardiomyocytes, skeletal myoblasts, and stem cells with apparent cardiomyogenic potential. Here we provide a review of studies wherein myocytes or stem cells with myogenic potential have been transplanted into the heart. In addition, issues pertaining to the tracking and functional consequences of cell transplantation are discussed.