Together with angiogenesis and gene therapy, cell transplantation is one of the newest treatments that have been proposed to improve the still grim outcome of patients with cardiac failure. The underlying rationale is that implantation of contractile cells into fibrous post-infarction scars can functionally 'regenerate' these areas. Primarily for practical reasons, autologous skeletal myoblasts have been the first to be tested in a clinical trial but other cell types can be considered, among which bone marrow stromal and hematopoietic stem cells are of particular interest because of their autologous origin and their purported transdifferentiation potential into cardiac and/or endothelial cells. However, several key issues still need to be addressed, including (i) the optimal type of donor cells, (ii) the mechanism by which cell engraftment improves cardiac function, actively (i.e., by increasing contractility) or passively (i.e. by limiting infarct expansion and remodelling), (iii) the optimisation of cell survival, and (iiii) the potential benefits of cell transplantation in non-ischaemic heart failure. Parallel to the numerous experimental studies designed to address these issues, initial clinical trials are underway or in preparation and, if properly designed and conducted, should allow to know whether the hopes raised by cellular therapy are met by clinically meaningful improvements in the outcomes of patients with heart failure. © 2002 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS.