This single arm study will assess the efficacy, safety and tolerability of once monthly administration of subcutaneous Mircera for the maintenance of hemoglobin levels in patients with chronic renal anemia not on dialysis.Patients will receive sc Mircera at a starting dose of 100, 120, 200 or 360 micrograms every 4 weeks, calculated from the last weekly dose of ESA previously administered. Subsequent doses will be adjusted to maintain hemoglobin levels within the target range. The anticipated time on study treatment is 3-12 months, and the target sample size is 100-500 individuals.