Objective: Iron and iodine, which are the two important micronutrients, are still deficient in a large number of women worldwide. This study aimed to examine the thyroid volumes of iron deficient, anemic women before and after correction of the anemia in a mildly iodine deficient environment. Material and Methods: Sixty six women aged 18-45 years were prospectively enrolled in this study. Inclusion criteria included serum hemoglobin (Hb) level <11.0 g/dL, ferritin level <13 ng/mL, thyroid hormones within normal reference ranges and negative thyroid antibodies. Oral iron supplement (567 mg ferrous sulfate, twice a day) for six months was prescribed and strongly recommended. All patients were re-evaluated at the end of the iron treatment. Results: Initially, the median (minimum/maximum) Hb and ferritin levels of patients were 10.2 g/dL (5.6/11.1) and 3.95 ng/mL (0.44/10.7), respectively. Six months later, median Hb and ferritin values increased significantly to 13.15 g/dL (9.3/15.6) (p<0.001) and 19.575 ng/mL (3.74/79) (p<0.001) respectively. Median thyroid volume decreased significantly from 15.705 mL (7.15/54.2) to 13.212 mL (6.11/52.8) (p<0.001). The patients were grouped according to the improvements in Hb and ferritin levels, initial thyroid gland volume, and response to the treatment. The reduction in thyroid gland size, at the end of the treatment, was more significant in patients with improvement in both Hb and ferritin levels as compared to those with improvement only in Hb levels (p<0.05). Conclusion: Iron may be responsible for efficient organification of iodine, active iodine utilization from thyroglobulin, and control of hyperkinetic blood-flow to the thyroid gland. The findings of this study support that other than iodine, iron supplementation has a significant effect on the regression of thyroid volume in women with iron deficiency anemia.