BackgroundWe determined whether postoperative intravenous (IV) iron supplementation could reduce transfusion rate in patients undergoing staged bilateral total knee arthroplasty (TKA). Furthermore, we examined whether hemoglobin (Hb) levels and iron profile differed between patients with and without postoperative IV iron supplementation. MethodsThis retrospective, comparative cohort study included 126 patients who underwent primary staged bilateral TKA during a single hospitalization. The second TKA was performed at a week’s interval. Group iron (n = 65) received IV iron immediately after each surgery, while patients in group no-iron (n = 61) received no iron after surgery. Transfusion rate, change in Hb levels, and iron profile including serum iron, ferritin, total iron binding capacity, and transferrin saturation were evaluated preoperatively; on postoperative days 1, 2, and 4 after the first TKA; and postoperative days 1, 2, 4, and 7, 6 weeks, and 3 months after the second TKA. ResultsThere were no significant differences in Hb levels and transfusion rate following staged bilateral TKA between patients with and without postoperative IV iron supplementation although serum iron profiles were improved in patients with IV iron supplementation. ConclusionPostoperative IV iron supplementation immediately after acute blood loss caused by TKA was not effective in improving the transfusion rate. Therefore, surgeons should use protocols other than postoperative IV iron supplementation for reducing the transfusion rate in patients undergoing staged bilateral TKA in a single hospitalization. Level of EvidenceIII.