Graft rejection has been a problem after bone marrow transplantation for patients with severe aplastic anemia (SAA). Ten children with SAA were conditioned for bone marrow transplantation from HLA-identical siblings, using cyclophosphamide (CY, 50 mg/kg) plus antithymocyte globulin (ATG, 15 mg/kg) for 4 successive days. Marrow was infused 36 h after the last dose of CY. Cyclosporin A and methotrexate were administered as graft-versus-host disease (GVHD) prophylaxis. All patients achieved durable engraftment at follow-up of 7-41+ months (mean, 25) without significant GVHD. Since investigators have used different sources, doses, and time schedules of ATG, we compared our results with other published reports. We conclude that CY/ATG conditioning is well tolerated and effective in children with SAA.