Myelodysplastic syndrome (MDS) with erythroid hypoplasia/aplasia has not yet been clearly defined, and in most patients it is mistaken for acquired pure red cell aplasia (PRCA). We report a patient with severe transfusion-dependent anemia (Hb 6.9 g/dl) and reticulocytopenia. WBC and platelet counts were normal. Bone marrow examination showed a marked trilineage dysplasia and a low percentage of erythroid precursors (3%). A diagnosis of MDS (refractory anemia according to FAB classification) with erythroid hypoplasia/aplasia was made. Repeated cytogenetic analysis of bone marrow showed normal karyotypes. Moreover, serial IgM serology and DNA analysis of the patient's sera for B19 parvovirus were negative. Other conditions known to be associated with erythroid aplasia were also absent. The patient failed hematinics and prednisone therapy. He next received r-HuEPO (200 U/kg three times weekly). This form of therapy achieved a rapid and complete erythroid response. He has remained in complete erythroid response after a 7-month period on maintenance therapy of 100 U/kg three times weekly. A review of the literature revealed only 15 well-documented cases of MDS with erythroid hypoplasia/aplasia. All had morphological evidence of myelodysplasia. These patients were predominantly elderly males, all required regular packed red cell transfusions, and had an unfavorable prognosis, mainly because of a high rate of blastic transformation (frequently preceded by a myeloproliferative phase). The mechanism of erythroid hypoplasia in this subgroup of MDS remains uncertain. However, laboratory and clinical data suggest the existence of an intrinsic stem cell defect. None of the patients received hematopoietic growth factors. To our knowledge, our patient is the first case of MDS with erythroid hypoplasia where r-HuEPO was successfully attempted. The description of more cases is necessary to delineate the value of r-HuEPO therapy in this rare variant of MDS. Am.