Treatment period 1:To demonstrate that switching HD subjects with a baseline haemoglobin (Hb) ≥ 10 g/dL and ≤ 13 g/dL from either subcutaneous (SC) or intravenous (IV) rHuEPO to IV darbepoetin alfa results in a mean Hb > 11 g/dL.

Treatment Period 2:To demonstrate that switching subjects with a Hb > 11 g/dL and ≤ 13 g/dL from once weekly IV darbepoetin alfa to once every 2 weeks (Q2W) maintains the mean Hb at > 11 g/dL.

Inclusion Criteria: -at least 18 years old - Diagnosis of chronic kidney disease (CKD) and receiving dialysis for at least 3 months prior to screening - Baseline Hb level greater than or equal to 10.0 g/dL and less than or equal to 13.0 g/dL - Adequate iron stores (defined as serum ferritin greater than or equal to 100 µg/L or transferrin saturation [TSAT] greater than or equal to 20%) - Stable IV (epoetin alfa or beta) or SC rHuEPO (epoetin beta) therapy 2 or 3 times per week for at least 8 weeks before screening (stable is defined as less than 25% change in weekly dose and no change in frequency or route) - All subjects must practice adequate contraception (in the judgment of the investigator) throughout this trial. Exclusion Criteria: - Received SC epoetin alfa in the 12 months before screening - Uncontrolled hypertension (diastolic blood pressure greater than 100 mmHg or systolic blood pressure greater than 180 mmHg on 2 separate occasions during screening) - Prior history (within 12 weeks before enrolment) of cardiovascular events including:

• acute myocardial ischemia;
• hospitalization for congestive heart failure;
• myocardial infarction. - Pregnant or breast-feeding women - Treatment with an investigational agent or device within 30 days before screening or scheduled to receive an investigational agent other than those specified by this protocol during the course of this study - Known sensitivity to any of the products to be administered during dosing - Disorder that compromises the ability of the subject to give written informed consent and/or to comply with study procedures