We report the surgical-pathologic findings in 15 adults who had a history of irradiation of the head and neck in childhood. These patients we selected for thyroid surgery because of a "cold" area or areas detected on 99mTc thyroid scan, with or without palpable thyroid abnormalities. Eight of the fifteen patients had thyroid cancer, and 3 had atypical adenomas. We found multiple lesions in 12 patients. Macroscopic and microscopic malignancy in a location different from the cold area or areas occurred in 5 of the 8 cancer patients. In vitro of these findings, we recommend that adults who received irradiation to the head and neck in childhood and who have been found to have an abnormal thyroid scan or thyroid examination, or both, have a total thyroidectomy...