Between February 1984 and August 1987, 10 patients with severe aplastic anemia were treated with bone marrow transplantation from HLA-identical sibling donors after preparation with cyclophosphamide (CY) 200 mg/kg and total lymphoid irradiation (TLI) 750 cGy. Ages ranged from 5 to 28 years (median 14 years). All patients were previously transfused. Median number of transfusions was 16 (range, 3-886). For post-transplant immunosuppression all patients were given cyclosporine and the last three patients received additional immunosuppression with short-term methotrexate. All patients had initial engraftment and survived for more than 3-46 months after transplantation. One patient developed significant acute graft-versus-host disease (GVHD) and three of nine recipients who survived more than 100 days developed chronic GVHD. One male patient who had received 21 transfusions from his marrow donor before transplantation suffered from persistent granulocytopenia. Otherwise all have Karnofsky performance scores of 90-100%. Although the number of patients is small, it appears that allogeneic bone marrow transplantation with the regimen of CY + TLI for preparation combined with cyclosporine (+ short-term methotrexate) for post-transplant immunosuppression is a promising modality for treatment of previously transfused patients with severe aplastic anemia.