Differentiated thyroid cancerc (DTC) which have very good prognosis are the most common endocrine malignancies. Radioactive iodine treatment (RIT) applied to selected patients after thyroidectomy is a highly effective treatment method. Post-treatment follow-up of these patients exhibits a great importance because of the higher relapse rates and development of distant metastases in some cases. In this review, the methods used in the follow-up DTC patients after RIT are reported.