Surveillance Study to Estimate the Incidence of Pure Red Blood Cell Aplasia Among Patients With Chronic Kidney Failure

Inclusion Criteria: * Patients with established CRF as an indication for the treatment of anemia * Patients who are receiving or are about to receive (within 1 month) a marketed erythropoietin (i.e., epoetin alfa \[EPREX/ERYPO/GLOBUREN\], epoetin beta \[NEORECORMON®\], or darbepoetin alfa \[ARANESP®\]) by the s.c. route of administration * Patients who are likely to continue to receive s.c. erythropoietin product(s) for at least 1 year. Exclusion Criteria: * Patients with a history of pure red cell aplasia or aplastic anemia * Patients who are experiencing unexplained loss or lack of effect to a recombinant erythropoietin product ongoing at the time of enrollment * Patients who have had prior recombinant erythropoietin treatment whose anemia had never responded (primary lack of efficacy) * Patients with a history of EPO antibodies prior to enrollment * Subjects who are currently receiving immunosuppressive medication (e.g., cyclosporine, tacrolimus, sirolimus, mycophenolic mofetil, azathioprine, or monoclonal antibodies) or corticosteroids at a dose corresponding to \>15 mg/day prednisolone * Subjects whose first s.c. exposure to any erythropoietin product was \>1 year prior to enrollment.