Conditioning Regimens for Patients With Severe Aplastic Anemia Transplanted With Marrow From an Unrelated Donor

Inclusion Criteria: * Life-threatening marrow failure of nonmalignant etiology; * failure to respond to the best available immunosuppressive treatment; * lack of a HLA-identical family member Exclusion Criteria: * Severe disease other than aplastic anemia that would severly limit the probability of survival during the graft procedure; * HIV seropositive patients; * clonal abnormalities or myelodysplastic syndrome;