exposed individuals had T, increments of <1.5 pg/dl. In addition, several ex- posed individuals with intact thyroid glands have periodically shown modest TSH elevations. These observations stimulated attempts to evaluate residual thyroid function in all exposed individuals (1,36). B. Methods 1. Thyroid Examinations Examinations included inspection, palpation, and auscultation of the neck and thyroid gland; notation of any clinical signs of thyroid dysfunction; quantitative assays of serum iodine, thyroid hormones, and iodoproteins; and special studies of thyroid function as described below. Suspected nodules were examined by other team physicians for confirmation and were recorded by description and full-scale drawings. Some nodules were so indistinct on initial examination that they were not evaluated further at the time but received special attention on subsequent surveys, often by the same physicians utilizing the medical records and annotated drawings as a basis for comparison. Since, in most cases, a diagnosis could not be firmly established without histopathologic evaluation, surgical exploration was usually recommended for patients with clinically suspicious findings. Age and general health status of these patients were important considerations in view of travel requirements. Surgery was sometimes deferred because of poor health and/or old age, favorable response of thyroid nodules to thyroxine therapy, or unavailability of the individual for close followup examinations. Those consenting to surgery were generally admitted to hospitals in the United States after initial evaluation at Brookhaven National Laboratory Medical Research Center. Preoperative thyroid studies included iodine uptake, scans, and determination of thyroid hormone and autoantibody levels. Aside from a few cases at Tripler Army Hospital in Honolulu, surgical procedures during the past decade were performed exclusively at Cleveland Metropolitan General Hospital. 2. Pathologic Evaluation All excised tissues were examined by the pathologists associated with each hospital where surgery was performed. In the past these have also included U.S. Naval Hospital, Guam; Ishoda Memorial Hospital, Majuro; and New England Deaconness Hospital, Boston. In addition to gross and microscopic pathologic evaluations, selected slides from each specimen were referred for review to a number of pathologists who had special expertise in diseases of the thyroid.* Working diagnoses for individual patients were assigned on the basis of evaluations obtained from all these sources at the time. *Drs. S. Warren (deceased), W.A. Meissner, and M. Legg (New England Deaconness Hospital, Boston, MA); J.D. Reid and M. Petrelli (Cleveland Metropolitan Gen- eral Hospital); J. Oertel (Armed Forces Institute of Pathology, Walter Reed Army Medical Center, Washington, DC); L.B. Woolner (Mayo Clinic, Rochester, MN); A.L. Vickery (Massachusetts General Hospital, Boston); L.V. Ackerman (S.U.N.Y. Stony Brook, NY); W. Hawk (Cleveland Clinic, Cleveland, OH); and D. Slatkin (BNL). - 55 =