Umbilical cord blood collected and cryopreserved at birth contains enough hematopoietic progenitor stem cells for engraftment. HLA identical sibling cord blood transplant has been performed for the first time, in a child with Fanconi anemia. Three years latter, this child is alive with a complete donor type bone marrow. Since this first attempt, several other patients with other diseases have been transplanted successfully. Cord blood banking is a safe and easy procedure. Due to the high proliferative capacity of neonatal hematopoietic progenitors and to the relative immunological functional immaturity of neonatal lymphocytes cord blood cells could be used for matched unrelated or partially mismatched transplants.