Inclusion Criteria:

• ≥ 18 years old
• diagnosis of CRI and not receiving dialysis therapy (must be predialysis)
• measured or estimated (using the Cockcroft-Gault formula) creatinine clearance (CrCl) of ≤ 70 mL/min, or GFR ≤ 60 mL/min (using the MDRD formula):
• Cockcroft-Gault formula: CrCl = (140 minus age in years) x (body weight in kg) serum creatinine (mg/dL) x 72.0 For women, the value will be multiplied by 0.85
• MDRD formula: GFR = 170 x [SCr]-0.999 x [Age]-0.167 x [0.762 if subject is female] x [1.180 if subject is black] x [sun] -0.170SAlb]-0.318
• mean Hgb < 11 g/dL during the screening/baseline period (if subject is not already receiving rHuEPO therapy)
• for subjects currently receiving rHuEPO therapy, the subject must have: a stable rHuEPO dose for the past month; and a rHuEPO frequency of once weekly.
• white blood cell and platelet counts within normal limits
• serum vitamin B12 and folate levels above the lower limit of normal range
• transferrin saturation (TSAT) ≥ 20% during the screening period
• availability for follow-up assessments
• subject must be able to comprehend and be willing to, or have legally accepted representative, give written informed consent for participation in the study

Exclusion Criteria:

• scheduled to initiate dialysis
• uncontrolled hypertension (diastolic blood pressure > 105 mm Hg or systolic blood pressure of > 180 mm Hg during the screening/baseline period on two separate measurements)
• clinically unstable in the judgment of the investigator (eg, subject is in the intensive care unit, immediately post-myocardial infarction, etc)
• scheduled to receive a living donor kidney transplant
• treatment of grand mal epilepsy within the past 6 months
• moderate to severe congestive heart failure (NYHA class III or IV)
• clinical evidence of severe secondary hyperparathyroidism (parathyroid hormone level > 1500 pg/mL)
• severe active chronic inflammatory process (eg, ulcerative colitis, peptic ulcer disease, rheumatoid arthritis, etc)
• currently receiving antibiotic therapy for systemic infection (enrollment may be postponed until the course of antibiotics has ended)
• known aspartate aminotransferase (AST) or alanine aminitransferase (ALT) greater than 3 times the upper limit of the normal range on more than one occasion within three months prior to screening
• known positive HIV antibody or hepatitis B surface antigen
• clinical evidence of current malignancy and/or receiving chemotherapy with the exception of basal cell or squamous cell carcinoma of the skin and cervical intraepithelial neoplasia
• active bleeding or RBC transfusion within eight weeks of enrollment
• androgen therapy within four weeks before enrollment
• known hematologic disease (eg, sickle cell anemia, myelodysplastic syndromes, hematologic malignancy, myeloma; hemolytic anemia, etc)
• any condition that is likely to affect subject compliance
• currently or previously (within 30 days) enrolled in investigational device or drug trial(s) or receiving investigational agent(s)
• the exception to this is if the subject was enrolled in another Aranesp™ or rHuEPO protocol
• pregnant or breast feeding women (women of child-bearing potential must be using contraceptive precautions)
• women planning to have a child during the study period
• known hypersensitivity to the active substance or any of the excipients