Myelodysplastic syndrome (MDS) with erythroid hypoplasia, a rare form of MDS, has not yet been clearly defined. We report here a 20-year-old woman with severe transfusion-dependent anemia and reticulocytopenia. White blood cells and platelet counts were normal. Bone marrow examination showed a low percentage of erythroid precursors (6%) and a marked dyserythropoiesis and dysmegakaryopoiesis. A diagnosis of MDS (refractory anemia according to the FAB classification) with erythroid hypoplasia was made. Cytogenetic analysis of the bone marrow and peripheral blood revealed a 46,XX,t(3;14)(p21.1;q24.1) translocation, which was confirmed by fluorescence in situ hybridization analysis. This translocation was detected in the apparently healthy younger brother, father, and aunt (father's sister) of the patient. Clonality of T cells in the patient was not confirmed by the polymerase chain reaction and heteroduplex temperature-gradient gel electrophoresis. IgM serology for B19 parvovirus was negative. Other conditions known to be associated with erythroid hypoplasia, such as thymoma, were not present. The patient failed to respond to immunosuppressive therapy (antithymocyte globulin and cyclosporin A). Administration of recombinant human erythropoietin improved her anemia. To our knowledge, this balanced translocation, namely t(3;14)(p21.1;q24.1), which is present both in the patient with MDS with erythroid hypoplasia and in the healthy members of the family, has not been defined previously.