[en] Radioiodine therapy is indicated in patients with differentiated thyroid carcinoma for eliminating of thyroid remnants after thyroidectomy and furthermore enables an efficient treatment of metastases and recurrences showing a radioiodine uptake. In our opinion exceptions can be made in patients with occult papillary carcinoma only. One of the most simple and effective methods of treating metastatic cancer today is the therapy with radioiodine in patients with metastatic differentiated thyroid carcinoma. Therefore radioiodine therapy should be performed consistently until ineffectiveness is proved. Side effects of radioiodine treatment are minimal, but not negliable. The use of radioiodine has therefore to be individually considered and in cases of metastatic cancer to be supported by a multimodal approach. (orig.)