Sixteen patients (ages 53 to 85) with myelodysplastic syndrome (MDS) were treated with recombinant human erythropoietin (rHuEPO) to observe its effects on hematopoiesis. All were transfusion dependent and had Hb levels less than 9.0 g/dl and less than 10% marrow blasts. Eight patients had refractory anemia (RA), one had refractory anemia with excess blasts (RAEB), and seven had refractory anemia with ringed sideroblasts (RARS). A response was defined as an increase in Hb by greater than 2 g/dl and/or a decrease in transfusion requirement by greater than 50%. Patients were considered to be evaluable if on study greater than two months. Three of thirteen evaluable patients had a response. One patient with RA had a sustained trilineage hematologic response with no evidence of disease progression. None of the patients had trouble with hypertension or with thrombotic events. This suggests than an occasional patient with MDS will respond to rHuEPO. In some patients, this may be beneficial clinically.