Background: C.E.R.A., a continuous erythropoietin receptor activator, is in development to provide anemia correction and stable maintenance of hemoglobin (Hb) levels at extended administration intervals in patients with chronic kidney disease (CKD). This study examined its efficacy and safety when administered up to once monthly in patients who have CKD and are on dialysis and randomly convert directly from epoetin ␣ or  one to three times weekly.Design, setting, participants, and measurements: In this three-arm, comparator-controlled, open-label, randomized, parallelgroup, Phase III study, 572 dialysis patients (>18 yr) who were receiving stable subcutaneous epoetin one to three times weekly were randomly assigned (1:1:1) to continue epoetin or to receive subcutaneous C.E.R.A. once monthly or twice monthly for 52 wk. Conclusions: Subcutaneous C.E.R.A. once or twice monthly successfully maintained tight and stable Hb levels in patients who were on dialysis and randomly converted directly from epoetin one to three times weekly.