Anemia is a common complication of inflammatory bowel diseases (IBD) This multicenter study tested the noninferiority and safety of a new intravenous iron preparation, ferric carboxymaltose (FeCarb), in comparison with oral ferrous sulfate (FeSulf) in reducing iron deficiency anemia (IDA) in IBD. Two hundred patients were randomized in a 2:1 ratio (137 FeCarb:63 FeSulf) to receive FeCarb (maximum 1,000 mg iron per infusion) at 1-wk intervals until the patients' calculated total iron deficit was reached or FeSulf (100 mg b.i.d.) for 12 wk. The primary end point was change in hemoglobin (Hb) from baseline to week 12. The median Hb improved from 8.7 to 12.3 g/dL in the FeCarb group and from 9.1 to 12.1 g/dL in the FeSulf group, demonstrating noninferiority (P= 0.6967). Response (defined as Hb increase of >2.0 g/dL) was higher for FeCarb at week 2 (P= 0.0051) and week 4 (P= 0.0346). Median ferritin increased from 5.0 to 323.5 mug/L at week 2, followed by a continuous decrease in the FeCarb group (43.5 mug/L at week 12). In the FeSulf group, a moderate increase from 6.5 to 28.5 mug/L at week 12 was observed. Treatment-related adverse events (AEs) occurred in 28.5% of the FeCarb and 22.2% of the FeSulf groups, with discontinuation of study medication due to AEs in 1.5% and 7.9%, respectively. FeCarb is effective and safe in IBD-associated anemia. It is noninferior to FeSulf in terms of Hb change over 12 wk, and provides a fast Hb increase and a sufficient refill of iron stores.