Fifty patients with aplastic anemia (AA) were treated with BMT or immunosuppressive therapy (IST). Twenty-one patients underwent BMT using cyclophosphamide (CY) and 7 Gy total lymphoid irradiation (TLI) and cyclosporin A (CsA) plus methotrexate (MTX). Actuarial survival is 71% at 5.3 years with an incidence of graft failure of 0% and of acute GVHD of 38.9%. Univariate analysis of variables influencing survival showed a trend for a poorer outcome in patients who received > 30 transfusions prior to BMT and in male recipients from female donors. Twenty-nine patients > 40 years of age or without matched siblings received antithymocyte/antilymphocyte globulin (ATG/ALG). Response rate to the first course of treatment was 46.4%. Subsequent courses of IST rescued 33% of patients who relapsed or had not responded. Actuarial survival is 62% at 8.6 years. In our experience both treatment strategies have given encouraging results although overall morbidity is higher in the IST group because 25% of patients are therapy or transfusion-dependent. The role of irradiation in the conditioning regimen of BMT patients, recently challenged, is discussed.