Haematopoietic stem-cell transplantation is used to treat many haematological cancers, but is limited by the lack of suitable bone-marrow donors, the risk of graft-versus-host disease (GVHD) and slow immune reconstitution. Umbilical-cord blood is an alternative source of haematopoietic stem cells that has recently been tested in both child and adult cancer patients. These studies have identified several advantages to umbilical-cord cell transplantation, including a lower incidence of GVHD. Umbilical-cord blood is therefore a promising alternative to bone-marrow-derived stem cells.