Thorough examination of complete thyroid glands from the autopsies of 218 people 50 years of age or younger, and 212 persons older than 80 years of age in a Swedish population showed that occult papillary thyroid carcinoma occurred in much the same frequency (about 7%) in the ages from the second decade. The youngest person with the lesion in question was 17 years of age. The prevalence of occult papillary thyroid carcinoma did not differ significantly between men and women. The tumors of the women were on an average larger than those of the men, and the tumors in the old were on an average larger than those in the young.