Thorough examination of complete thyroid glands from the autopsies of 218 people .ltoreq. 50 yr of age and 212 persons > 80 yr 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 2nd decade. The youngest person with this lesion was 17 yr 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.