Iodine-131 (I-131) has been used in the therapy of well-differentiated thyroid cancer for over 60 years and has been an important component in the management of well-differentiated thyroid cancer. Differentiated thyroid carcinoma (DTC) is one of the most curable cancers, associated with a 10-year survival rate of 80~95%. Total (or near-total) thyroidectomy followed by radioiodine ablation is considered to be the ideal treatment for the high risk tumors. The selective use of radioactive iodine on the basis of clinicopathologic features that define the risk of recurrence and disease specific mortality is generally recommended in many kinds of international or institutional guidelines. However, recurrence in the thyroid bed or cervical lymph nodes develops in 5~20% of patients with DTC and some patients develop distant metastatic disease decreasing the 10-year survival of patients by 50%. Unfortunately, many of these patients ultimately die from advanced disease and other therapeutic approaches are needed. The goals of therapy for those patients should be to improve survival, relieve symptoms, and decrease the morbidity of disease progression and limit the morbidity associated with therapy. Safe practice of radioiodine treatment should be balanced with the benefit and the risk. This review will address the results of the radioiodine treatments in patients with the advanced thyroid cancer with the recent clinical trials.