C.E.R.A., a continuous erythropoietin receptor activator is approved for the treatment of anemia in patients with chronic kidney disease (CKD). The ARCTOS (administration of C.E.R.A. in CKD patients to treat anemia with a twice-monthly schedule) phase 3 study demonstrated the efficacy and safety of C.E.R.A. in correcting anemia when administered once every 2 weeks (Q2W) subcutaneously in patients with CKD not on dialysis. We assessed the feasibility and long-term safety of converting patients who responded to treatment with C.E.R.A. Q2W to C.E.R.A. once every 4 weeks (Q4W) during a 24-week extension period. After the core ARCTOS study period (28 weeks), 296 patients entered the 24-week extension period. At week 29, patients who responded to C.E.R.A. Q2W during the core period were rerandomized to receive subcutaneous C.E.R.A. Q2W or Q4W. Patients in the comparator arm could receive darbepoetin alfa once weekly or Q2W. Dosage was adjusted to maintain hemoglobin (Hb) between 11 and 13 g/dL. Mean Hb levels remained stable in all groups, and were comparable at the end of the extension period (mean [standard deviation], C.E.R.A. Q2W, 11.92 [0.90] g/dL; C.E.R.A. Q4W, 11.70 [0.86] g/dL; darbepoetin alfa, 11.89 [0.98] g/dL). Mean within-patient standard deviation values for Hb were also comparable in all groups (0.66, 0.62, and 0.65 g/dL for C.E.R.A. Q2W, C.E.R.A. Q4W and darbepoetin alfa, respectively). All treatments were well tolerated. Subcutaneous C.E.R.A. Q4W is safe and effective in maintaining stable Hb levels in patients with CKD not on dialysis following correction with subcutaneous C.E.R.A. Q2W.