This observational study will evaluate the course of treatment, the efficacy on anemia and the safety of Mircera (methoxy polyethylene glycol-epoetin beta) in patients with chronic kidney disease on dialysis. Eligible patients will be on either haemodialysis or peritoneal dialysis and treatment-naïve for or having had prior therapy with erythropoiesis stimulating agents (ESA). Data will be collected from each patient for 12 months.