We report on two Korean patients who developed pure red-cell aplasia (PRCA) due to anti-erythropoietin (EPO) antibodies. The first patient became refractory to EPO treatment after a good response for an initial 26 months. Anti-EPO antibodies were detected by enzyme linked immunosorbent assay (ELISA) and by radioimmunoprecipitation (RIPA), and these were found to inhibit erythroid colony formation by in vitro bioassay. In the second patient, the anemia became aggravated, accompanied by thrombocytopenia and wheals appeared at the EPO injection site 3 months after the initiation of subcutaneous EPO treatment. Anti-EPO antibodies were detected by ELISA, and the patient showed a partial response to the second corticosteroid treatment course. Our cases demonstrate that PRCA due to anti-EPO antibodies becomes an important issue in Asians as well as in Caucasians.