A 15-year-old, 50 kg weight patient with CML had a myeloblastic transformation which reverted to Ph negative remission with intensive chemotherapy 5 years after diagnosis. Umbilical cord blood (UCB) from an HLA-haploidentical sister had been frozen 2 years and 9 months before, as she had no HLA-identical sibling and no suitable unrelated donor had been found. UCB transplant was selected on the basis of previous general experience with this kind of transplant, lack of a better choice of donor, and likelihood of a prompt relapse of the disease without delay and the patient developed grade II aGVHD as well as severe CsA toxicity which required discontinuation of the drug, anti-IL2r being given instead. Subsequently she only had histologic evidence of cGVHD and 1.5 years after the transplant she remains in complete hematologic remission with full chimerism and without evidence of the bcr/abl fusion gene. This case illustrates further possibilities of allo-transplantation using UCB.