The primary objective of this study is to examine the efficacy and safety (cardiovascular) of an investigational intravenous (IV) iron, ferric carboxymaltose (FCM), compared to IV iron sucrose (Venofer) in subjects who have iron deficiency anemia (IDA) and impaired renal function.

Inclusion Criteria:

• Male or female subjects > or = to 18 years of age.
• Chronically impaired renal function.
• Screening visit central laboratory hemoglobin < or = to 11.5 g/dL.
• Screening ferritin < or = to 100 ng/mL or < or = to 300 when transferrin saturation (TSAT) is < or = to 30%.
• If on an erythropoiesis stimulating agent(ESA) a stable dose (+/- 20%) for 4 weeks prior to randomization.

Exclusion Criteria:

• Known hypersensitivity reaction to any component of ferric carboxymaltose (FCM) or Venofer.
• Previously randomized in a clinical study of Ferric Carboxymaltose (FCM).
• Requires dialysis for treatment of chronic kidney disease OR is being considered for initiation of dialysis during the time period of this trial.
• No evidence of iron deficiency.
• Any non-viral infection.
• AST or ALT at screening as determined by central labs greater than 1.5 times the upper limit of normal.
• Known positive hepatitis with evidence of active disease.
• Received an investigational drug within 30 days of screening.
• Alcohol or drug abuse within the past 6 months.
• Hemochromatosis or other iron storage disorders.
• Estimated life expectancy of less than 6 months, or for cancer patients, an ECOG Performance Status greater than 1.
• Any other laboratory abnormality, medical condition or psychiatric disorder which in the opinion of the investigator would put the subject's disease management at risk or may result in the subject being unable to comply with study requirements.
• Pregnant or sexually-active female subjects who are not willing to use an acceptable form of contraception.