Twenty-five children undergoing surgery for thyroid carcinoma, were compared in a retrospective study. Clinical characteristics and disease course were detailed in three groups. In the first of 11 patients, a lobo-isthmusectomy was performed for a thyroid nodule, exept two cases of total thyroidectomy (TT). Papillary carcinoma was diagnosed on histologic findings. Preoperative cytology and peroperative frozen section examination were inadequate for diagnosis. All children had a complete remission after treatment. In the second group, 10 children had evident thyroid carcinoma with cervical lymph node metastases, and lung metastases in two. Microscopical;ly, there were diffuse sclerosing variant or multifocal papillary carcinoma. A TT with central node dissection was performed in all, with a lateral lymph node dissection in 9. Treatment included radioiodine therapy and thyroxin suppression therapy. Three patients had a postoperative recurrent laryngeal palsy, one hypoparathyroidism. Reoperation was carried out in 4 for cervicomediastinal lymph node recurrence. All patients are alive, with a complete remission, exept for the two patients with lung metastases. In this group of aggressive tumors, a complete cure was possible with combination of extended, sometimes repeated, surgery and radioiodine therapy. In the last group, 4 patients had a medullary carcinoma. One presented with a thyroid nodule. The others were asymptomatic with a positive pentagastrin test during biological screening for familial disease. Two patients with lymph node metastases had a persistent pathologic calcitonin test despite a TT with complete central and lateral lymph node dissection. Early genetic screening in family members is the only way to perform a curative thyroidectomy in a prepathologic stage.