This prospective, multicenter, observational study will evaluate the impact of comorbidities on hemoglobin stability in chronic kidney disease patients on dialysis treated with Mircera (methoxy polyethylene glycol-epoetin beta). Eligible patients will be followed for 6 months of treatment.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Chronic kidney disease patients on hemodialysis or hemodiafiltration for at least 3 months
• Previously treated with an erythropoietin stimulating agent (ESA)
• Patient for whom the investigator decided to initiate treatment with Mircera for medical reasons
• Last hemoglobin level before initiation of Mircera within the range of 10-12 g/dL

Exclusion Criteria:

• Current participation in a clinical trial on renal anemia

Chronic kidney disease patients on hemodialysis or hemodiafiltration for at least 3 months, previously treated with an erythropoietin stimulating agent (ESA) and for whom treatment with Mircera is indicated