Objective: To evaluate the efficacy and safety of intravenous iron supplementation in patients with recurrent iron deficiency anemia (IDA) . Methods: This retrospective analysis of 90 patients with recurrent IDA from May 2012 to December 2021 was conducted, comparing the efficacy and safety of the intravenous iron therapy group and the oral iron therapy group. Results: Among the 90 patients with recurrent IDA, 20 were males and 70 were females, with a median age of 40 (range: 14-85) years. A total of 60 patients received intravenous iron supplementation and 30 received oral iron supplementation. The hematologic response rates in the intravenous iron group were significantly higher than those in the oral iron group at 4 and 8 weeks after treatment [80.0% (48/60) vs 3.3% (1/30) and 96.7% (58/60) vs 46.7% (14/30), all P<0.001, respectively]. The median increase in hemoglobin levels was also significantly higher in the intravenous iron group than in the oral iron group [38 (4, 66) g/L vs 7 (1, 22) g/L at week 4 and 44.5 (18, 80) g/L vs 19 (3, 53) g/L at week 8, all P<0.001]. The intravenous iron group had a significantly higher proportion of patients who achieved normal hemoglobin levels than the oral iron group (55.0% vs 0 and 90% vs 43.3%, all P<0.001, respectively). Iron metabolism indicators were tested before and after 8 weeks of treatment in 26 and 7 patients in the intravenous and oral iron groups, respectively. The median increase in serum ferritin (SF) levels in the intravenous iron group 8 weeks after treatment was 113.7 (49.7, 413.5) µg/L, and 54% (14/26) of these patients had SF levels of ≥100 µg/L, which was significantly higher than the median increase in SF levels in the oral iron group [14.0 (5.8, 84.2) µg/L, t=4.760, P<0.001] and the proportion of patients with SF levels of ≥100 µg/L (P=0.013). The incidence of adverse reactions was 3.3% (2/60) in the intravenous iron group, which was significantly lower than that in the oral iron group [20.0% (6/30), P=0.015]. Conclusion: Intravenous iron supplementation is more effective for hematologic response, faster hemoglobin increase, and higher iron storage replenishment rates compared with oral iron supplementation in patients with recurrent IDA, and it is well tolerated by patients.