A Study to Observe the Number of Patients Who Develop Pure Red Cell Aplasia (PRCA, a Rare Form of Anemia) While Receiving Epoetin Alfa or Other Recombinant Erythropoietins

- Male or female patients of legal age to give consent according to local standards

- Patients must be receiving or about to receive treatment with an erythropoietin as part of a pre-existing treatment plan for their chronic renal (or other) disease

- Physicians treating the patients must agree in advance to document any appearance of pure red cell aplasia (PRCA) such that information and details of the case may be reported to regulatory agencies (with patient identification protected)

- If required by local ethics committees, patients must give consent to permit the collection of de-identified personal data for the specific purpose of this study

- Patients who are unable to complete future follow-up visits

- Patients who when entering the study have any of the following symptoms of pure red cell aplasia (PRCA): Loss of effectiveness of erythropoietin or low number of immature red blood cells while on erythropoietin as shown by a blood test or bone marrow examination

- Patients with a history of PRCA or loss of effectiveness with erythropoietin at the time of enrollment into the study

- Patients whose anemia did not respond to previous treatment with an erythropoietin

- Patients with a history of antibodies to erythropoietin prior to entering the study