During renal injury, stem cells derived from the circulation as well as resident stem cells may contribute to renal repair. Preliminary studies suggest the possibility to exploit this regenerative potential of stem cells for therapeutic purposes. This may be achieved either by administration of ex vivo expanded populations of mesenchymal stem cell or by strategies aimed to expand and differentiate local progenitor/stem cell populations. There is a general agreement that the beneficial effect of ex vivo expanded stem cell administration in acute renal injury is due to the generation of an environment that favours proliferation of dedifferentiated epithelial cells surviving the injury or of resident stem cells.