IN 1945 we (1) presented a nine-year study of the incidence of thyroid carcinoma in goiter at the Illinois Research Hospital and found that in 192 patients with nontoxic nodular goiter having thyroidectomy, the incidence of carcinoma was 17.1 per cent. This figure appeared unusually high because, prior to this time, investigators were reporting the incidence of thyroid carcinoma in all types of goiter without breaking down the figures to show the incidence in the different types of goiter. The present study, including all patients observed during the past seventeen years (1936–1952 inclusive), is presented to re-evaluate and compare the trends between our original report, 1936 to 1944 inclusive, and the subsequent period, 1944 to 1952 inclusive. During the seventeen years between 1936 and 1952 inclusive, 1,429 thyroidectonry operations for all types of goiter have been performed at the Illinois Research Hospital (Table 1). Seventy-five cases of carcinoma have been encountered—an incidence of 5.2 per cent ...