The authors investigated the incidence of antithyroglobulin antibodies and antibodies and antimicrosomal antibodies measured by tanned red cell hemagglutination method in subjects suffering from various thyroid disorders. 1) In 15 normal patients, neither suffering from any thyroid diseases nor from any other autoimmune disorders, the antithyroglobulin antibodies were all negative, but the antimicrosomal antibody was positive only in one patient(6.7%). 2) The antithyroglobulin antibodies were positive in 31.5%(34 patients) of 108 patients with various thyroid diseases, and the antimicrosomal antibodies were positive in 37.0%(40 patients). 3) of the 25 patients with Graves' diseases, 7 patients(28.0%) showed positive for the antithyroglobulin antibodies, and 9(36.0%) for the antimicrosomal antibodies. There was no definite differences in clinical and thyroid functions between the groups with positive and negative results. 4) Both antibodies were positive in 16(88.9%) and 17(94.4%) patients respectively among 18 patients with Hashimoto's thyroiditis, all of them were diagnosed histologically. 5) Three out of 33 patients with thyroid adenoma showed positive antibodies, and 3 of 16 patients with thyroid carcinoma revealed positive antibodies. 6) TRCH antibodies demonstrated negative results in 2 patients with subacute thyroiditis, but positive in one patient with idiopathic primary myxedema. 7) The number of patiencs with high titers(>l:802) was 16 for antithyroglobulin antibody, and 62.5%(10 patients) of which was Hashimoto's thyroiditis. Thirteen(65.0) of 20 patients with high titers(>l:802) for antimicrosomal antibody was Hashimoto's thyroiditis. TRCH test is a simple, sensitive method, and has high reliablity and reproducibility. The incidences and titers of antithyroglobulin antibody and antimicrosomal antibody are especially high in Hashimoto's thyroiditis.