This report exemplified a success of unrelated CBT in a two-month-old boy with Wiskott-Aldrich Syndrome. Umbilical cord blood was chosen as the stem-cell source because of its immediate availability and reduced tendency to cause GVHD. The conditioning regimen was cyclophosphamide, busulfan, and antithymocyte globulin. GVHD prophylaxis consisted of cyclosporin and methylprednisolone. The patient received an HLA 1-locus-mismatched cord blood unit, and the total number of infused nucleated cells was 11.14 x 10(7)/kg. Neutrophil engraftment was achieved on day +11, and a platelet count greater than 50 x 10(9)/L was achieved on day +71. He is currently alive and doing well at nine months post-transplant and free of any bleeding episodes. This case suggests that unrelated donor CBT may be safe and technically feasible, even in early infancy, when an appropriately matched related or unrelated donor is unavailable.