Thyroid cancer is the third most common solid tumor in children and adolescents. A review was made of the data on 540 such patients reported from nine large centers renowned for their experience with thyroid cancer. In respect to the pathogenesis the only factor conclusively known to promote development of thyroid cancer in the pediatric age group is irradiation, as documented by the Chernobyl experience. The evidence indicates that thyroid carcinoma in the pediatric age group is a biologically independent and more aggressive entity than in adults; paradoxically the prognosis is good. In the great majority of cases the only presenting sign was a neck mass. In a high percentage (60-80%) there were also palpable lymph nodes. The findings regarding lung metastases were not clear-cut: in most series they were present in about 10%, with a high of 28% in one group and a low of 5% in another group. Papillary carcinoma or the follicular variant of papillary carcinoma were the dominant histologic types, pure follicular carcinoma being found much less frequently than among adults with thyroid cancer. Despite the relatively advanced stage of the disease upon diagnosis, only 13 patients died of the disease, 12 to 33 years postoperatively. Recurrence rates ranged between 10% to 35%, with involvement of the lateral neck, thyroidal bed or distant sites 3 to 33 years after treatment; most failures responded to further surgery or radioactive iodine. There is almost general agreement that surgical intervention should consist of total or near total thyroidectomy despite the high rates of recurrent laryngeal nerve paralysis and hypocalcemia. In regard to neck metastases less than radical surgery has proved during the years to be sufficiently effective. Radioactive iodine, used by all at some stage of management for treatment purposes, should be used prophylactically only after due consideration in view of possible teratogenicity.