The therapeutic approach to patients with differentiated thyroid carcinoma has become a major issue of controversy in the last decade. The major aspects are the surgical resection and adjuvant therapy, particularly the need for thyroid ablation following surgery. According to the risk group definition suggested by Cady in 1979, low risk patients may be subjected to lobectomy only, then placed on thyroxine treatment and followed clinically with thyroglobulin determination. High risk patients should undergo total thyroidectomy and 131I ablation. Follow-up should include thyroxine treatment and an annual whole body 131I scan. In the event of residual thyroid tissue or functional metastases, 131I treatment is to be given.