Transplantation of cord blood (CB) is increasingly used as therapy for patients whose own marrow is affected by genetic mutations that prevent the development of normal cells of the blood or immune tissues, or for patients whose marrow has been destroyed in the course of treatment for leukaemia and other malignancies. CB is a rich source of haematopoietic stem cells, can be easily harvested and stored in frozen aliquots in a CB bank. The first public CB bank was established in 1993 allowing unrelated CB transplantation to become an option for patients lacking a suitable adult donor. Today, the results of CB transplantation are comparable to those of bone marrow transplants with several important advantages: the graft is available ‘off the shelf’, thereby reducing the waiting time, and the requirements of human lecucoyte antigen (HLA) matching are less restrictive than those of adult sources. The reduced requirement for HLA matching allows transplants between incompletely matched donors and recipients, thus reducing the size of the inventory required at the national level. This also mitigates the disadvantage encountered by persons of rare HLA genotypes or those who do not belong to populations of North Western European descent. Finally, national CB programmes can easily make available for research individual surplus units not meeting minimal criteria for clinical use.