A clinical review of the incidence and features of subacute thyroiditis was undertaken from January 1, 1982 through September 30, 1984 at a general hospital in southern Ibaraki where 11, 207 new outpatients were seen. Our records showed 40 cases of thyroid disorders: 11 of subacute thyroiditis, 5 of malignant tumor, 4 of benign tumor, 3 of Basedow's disease, 2 of Hashimoto's disease, 2 of simple goiter and 13 of undetermined goiter. Subacute thyroiditis is, therefore, a more common thyroid disorder than is generally supposed. Female predominated in a ratio of 4.5:1. Most of the patients were 45 to 55 years old. The incidence of subacute thyroiditis was highest from July to September.