Nodules were found in 1108 subjects who received childhood radiation for benign conditions of the cervical area at our institution. This is 37.5% of 2958 subjects, out of a total of 5379, for whom there is follow-up information. Of the 848 subjects who have had thyroidectomies, 297 (35.0%) had thyroid cancer. In addition to thyroid tumors, salivary, neural, and probably parathyroid tumors also occurred as a late consequence of childhood radiation. Prospective studies of the subjects indicate that thyroid nodules are continuing to occur at a constant rate. The measurement of serum thyroglobulin is helpful in identifying individuals for whom the risk of developing a nodule is increased. Follow-up of patients with nonsurgically-treated nodules indicates that some of their nodules are progressive. At the present time there is no indication that radiation-induced cancers behave differently than ones in other settings. However, some of their characteristics, especially their multicentricity and occurrence in younger individuals, indicate that continued follow-up is necessary. On the basis of the data generated by the follow-up program at our institution and programs elsewhere, recommendations for screening, treatment, and follow-up are made. The recommendations stress the importance of estimating risk based on radiation dose, previous tumors, and serum thyroglobulin, in arriving at clinical decisions for these subjects.