The current treatment for heart failure is inadequate for a large number of patients who do not qualify for heart transplantation or innovative surgical therapy. Cellular augmentation of damaged myocardium has been actively investigated in the past decade. Cells best suited for the task are skeletal myoblasts and bone morrow mesenchymal stem cells. Both cell types are autologous, abundant, and easy to harvest. The focus of early human trials will be to establish the safety of an effective cellular dose. Trials conducted with an inadequate cellular dose may discredit cell therapy because of lack of effect but, more importantly, may provide a false sense of safety because of a lack of adverse events secondary to a small inoculating dose.