OBJECTIVES: To compare the safety and efficacy of iron carboxymaltose with ferrous sulfate to treat iron deficiency anemia in the post partum. METHODS: Patients were randomized (2:1 ratio) to receive iron carboxymaltose (up to 3 weekly doses of 1000 mg maximum, applied in 15 min; n=227) or ferrous sulfate (100 mg twice daily, 12 weeks; n=117). Changes in hemoglobin and iron stores up to week 12 were analyzed. RESULTS: Iron carboxymaltose was as effective as oral iron sulfate in changing hemoglobin, despite the much shorter treatment period (2 weeks vs 12 weeks). Ferritin levels were significantly higher. Except for injection site burning, iron carboxymaltose was better tolerated than ferrous sulfate, mainly concerning gastrointestinal side effects. There were no safety concerns identified in breast-fed infants. CONCLUSION: Parenteral iron carboxymaltose is a safe and effective treatment option for postpartum anemia, with advantages of a shorter treatment period, better compliance, rapid normalization of iron storages, and lower incidence of gastrointestinal side effects.