A survey to determine the incidence of overt thyroid disorders and of thyroid autoantibodies was conducted in one population in Shimane Prefecture. Three in 570 male subjects (0.5%) and twelve in 672 female subjects (1.8%) had overt thyroid disorders. Eight were cases of hyperthyroidism, three were diffuse or nodular goiter, another three were postoperative states of struma and the other was a case of overt hypothyroidism. We examined antithyroglobulin antibodies (TG) and thyroid microsomal antibodies (MS), excluding the 15 patients with overt thyroid disorders. Eight out of 567 males were positive for TG and thirty-two were positive for MS. Twenty-five out of 660 females were positive for TG and seventy-three were positive for MS. The incidence of TG and/or MS in females was thus higher than in the males. Age-specific incidence of circulating thyroid antibodies gradually increased in those over 40 years of age.