The last few years have witnessed a growing interest in regenerative therapy of the failing heart by cell transplantation. Initial studies with skeletal myoblasts were conducted more than 10 years ago. However, the potential of bone marrow derived cells has more recently led to a flurry of experimental studies generating overall positive but occasionally conflicting results. The ethics of initiating clinical trials with stem cells in patients with heart failure has been questioned. Although laboratory research attempts to overcome a number of questions surrounding the usefulness and safety of cell therapy, the accumulated body of evidence warrants implementation of clinical trials. The earliest of these have now documented the feasibility of cell therapy. It is now appropriate to conduct safety and efficacy studies which, if carefully done, should allow assessment of the extent to which this concept of regenerative therapy can be made a clinical reality.