This study investigated the effects of radioiodine (RAI) therapy on fertility-related hormones, particularly anti-Müllerian hormone (AMH), and menopause in women with differentiated thyroid cancer (DTC). Materials and Methods: We recruited 46 women with regular menstrual cycles who underwent total thyroidectomy for DTC. After excluding those who were menopausal before surgery, 35 patients in the RAI group and seven in the control group were analyzed. AMH levels were measured at baseline, 6 months, 9 months, and 1 year post-operation. Statistical analyses included Kruskal–Wallis tests and linear mixed model. Results: The Kruskal–Wallis test showed no significant difference in AMH changes between RAI doses (p=0.62). Age was significantly associated with AMH levels, with corresponding to a decrease of 0.18 ng/mL per year (p＜0.001).No significant difference in AMH levels was observed between the RAI and control groups after adjusting for age and baseline AMH (p=0.62). At 6 months after surgery or RAI, AMH declined in 57.1% (4/7), 60.0% (9/15), and 50.0% (9/18) in the control, 30 mCi, and 50 mCi groups, respectively. Among single RAI-treated patients with long-term follow-up, AMH levels recovered to baseline or higher in 50.0% (2/4), 0.0% (0/1), and 42.9% (9/19) in the control, 30 mCi, and 50 mCi groups, respectively. Conclusion: RAI therapy in patients with DTC showed no significant impact on AMH levels compared to controls. Larger studies with longer follow-ups are needed to assess its long-term effects on fertility.