Cord blood is a rich source of hematopoietic stem cells and progenitors cells, and cord blood transplantation has been used to treat both malignant and non-malignant disorders. In the Early Edition of the Proceedings of the National Academy of Sciences Broxmeyer et al. report analysis of the efficiency of recovery of stem cells from cord blood after 15 years of cryopreservation (Proc Natl Acad Sci USA 2002, 10.1073/pnas.0237086100). Extended freezing periods appeared to have no adverse effects on the recovery of progenitor populations or their renewal and proliferative capacities in culture. Furthermore, CD34+ cells isolated from cord blood were able to repopulate the hematopoietic system in vivo, when injected into sublethally irradiated non-obese diabetic (NOD)/severe combined immunodeficient (SCID) mice.