Recombinant human granulocyte colony-stimulating factor (rhG-CSF) and erythropoietin (rhE-PO) were used to treat ten patients with myelodysplastic syndromes (MDS). None of the patients showed a favorable response in erythrocyte and platelet counts following 10 weeks' treatment, although favorable responses in neutrophil counts were observed in eight of ten patients (80.0%) and in seven of eight patients (87.5%) following 2 weeks' and 10 weeks' treatment, respectively. However, one patient with refractory anemia had a delayed favorable response in erythrocyte and neutrophil counts at week 14 in spite of the cessation of combination therapy at week 10. These results indicate that combination therapy with rhG-CSF and rhEPO is not beneficial to patients with MDS, based on the presently used protocol.