Background: The Australian Iron Status Advisory Panel advocates dietary intervention as the first treatment option for mild iron deficiency [serum ferritin (SF) = 10-15 μg/L]. However, there appear to be no studies on the efficacy of dietary treatment for iron deficiency. Objective: We compared the effects of iron supplementation and of a high-iron diet on serum ferritin (SF) and hemoglobin in iron-deficient women of childbearing age. Design: Forty-four iron-deficient women (SF > 15 μg/L or SF = 15-20 μg/L plus serum iron > 10 μmol/L and total-iron-binding capacity <68 μmol/L) and 22 iron-replete women (hemoglobin ≤ 120 g/L and SF < 20 μ/L) matched for age and parity categories were enrolled and completed 7-d weighed food records at baseline. The iron-deficient women were randomly allocated to receive iron supplementation (105 mg/d; supplement group) or a high-iron diet (recommended intake of absorbable iron: 2.25 mg/d; diet group) for 12 wk. Hematologic and dietary assessments were repeated at the end of the intervention and again after a 6-mo follow-up. Results: Mean SF in the supplement group increased from 9.0 ± 3.9 μg/L at baseline to 24.8 ± 10.0 μg/L after the intervention and remained stable during follow-up (24.2 ± 9.8 μg/L), whereas the diet group had smaller increases during the intervention (8.9 ± 3.1 to 11.0 ± 5.9 μg/L) but continued to improve during follow-up (to 15.2 ± 9.5 μg/L). Mean hemoglobin tended to improve in both intervention groups, but the change was only significant in the supplement group. Conclusions: In iron-deficient women of childbearing age, a high-iron diet produced smaller increases in SF than did iron supplementation but resulted in continued improvements in iron status during a 6-mo follow-up.