Allogeneic hematopoietic cell transplantation from a CCR5 Δ32/Δ32 unrelated donor, performed for the first time in the "Berlin patient", provides the only evidence to date of long-term control of HIV infection. Stringent criteria to select human leukocyte antigen (HLA)-matched conventional donors and low prevalence of the CCR5 Δ32/Δ32 homozygous genotype (<1%) made the pursuit of "patient number 2" unsuccessful for many years. Cord blood (CB) transplantation allows more permissive HLA-matching criteria, making the search for HLA-compatible Δ32/Δ32 CB units potentially feasible for transplantation of HIV-infected individuals.