We retrospectively analyzed the outcome of bone marrow transplantation (BMT) performed in 26 patients with Wiskott-Aldrich syndrome (WAS) in one center. Twenty-eight transplantation procedures were performed. Ten unselected patients received unmanipulated marrow from a donor with genetically identical human leukocyte antigen (HLA). Eight patients were cured and survive 1.5 to 16.5 years after BMT. One patient successfully received a T-cell-depleted marrow from a matched unrelated donor. Sixteen patients were selected to receive a related HLA partially incompatible BMT because of the occurrence of life-threatening complications from the WAS (i.e., refractory thrombocytopenia, autoimmunity including vasculitis and sepsis). All but one received T-cell-depleted marrow after a conditioning regimen of busulfan and cyclophosphamide. One patient had two BMTs. Engraftment occurred in 12 of 17 attempts. The addition of monoclonal antibodies to lymphocyte function-associated antigen-1 and CD2 molecules appeared to improve engraftment. Six patients were long-term survivors, whereas others died of viral infections (n = 7), among which Epstein-Barr virus-induced B-lymphocyte proliferative disorder was predominant. Delay in development of full T- and B-cell functions accounted for severe infectious complications. These results confirm the excellent outcome of HLA genetically identical BMT in WAS, whereas BMT from HLA partially incompatible donors should be strictly restricted to patients with severe complications of WAS.