To evaluate the therapeutic potential of hematopoietic growth factors (HGFs) during immunosuppressive treatment (IST) of severe aplastic anemia (SAA), 38 patients with newly diagnosed SAA received IST alone (group I), or IST plus recombinant human erythropoietin and granulocyte-macrophage colony-stimulating factor (rhEPO + rhGM-CSF) (group II). Eleven patients in each group received antilymphocyte globulin (ALG) for IST, and eight patients in each group received cyclosporine (CSA). Complete remission rates at one year were 26% and 74% for group I and group II patients, respectively. The ALG-treated subgroup showed the greatest differences between treatments. Compared with patients receiving ALG alone, patients treated with ALG plus HGFs had significantly better one-year survival (100% vs. 54.5%, P < 0.05), complete remission rates (91% vs. 36%, P < 0.05), more rapid and complete hematologic recovery, greater reductions in transfusion requirements, and lower infection rates. The data suggest a potential role for rhEPO + rhGM-CSF therapy in SAA patients receiving IST.