Patients with relapsed acute myeloid leukemia following autograft have a poor prognosis. The possibility of allograft is frequently time-limited, as the disease reappears before a stem cell donor can be found in the worldwide registries. Cord blood transplantation is a new therapeutic approach, since cord blood units are rapidly available. The authors show how a relapsed chemotherapy-refractory patient was successful transplanted with a mismatched cord blood unit after reduced-intensity conditioning. Twenty-three months after transplantation, the child is in continuous complete remission and has full donor chimerism and no signs of chronic graft-versus-host disease.