We report a case of pure red cell aplasia (PRCA) subsequent to an allogeneic bone marrow transplantation with a major ABO mismatch, which was resistant to the standard treatment options such as plasma exchange, erythropoietin and changes in the immunosuppressive treatment. Accordingly, two cycles of Rituximab therapy were administered without success. The patient had a chronic graft-vs.-host disease of the liver, which meant that an additional donor leukocyte infusion could not be introduced. Instead, purified CD34(+) cells were administered after fludarabine and antithymocyte globulin therapy. As a result, the PRCA was resolved and the antidonor isohemagglutinin titer became undetectable.