Objective To investigate the cause, the clinical manifestation, the diagnosis and the treatment of subacute thyroiditis. Methods The medical history, clinical characteristics, laboratory data, nuclear medicine tests and treatment of 76 cases of subactue thyroiditis were analyzed. Results Subacute thyroiditis was more common in women than men, and 76 3% cases with subacute thyroiditis occurred during 30～49 years old. Almost all cases were characterized by enlargement of the thyroid with pain and tenderness, 49 cases of which showed that radioiodine uptake was low with increased serum thyroid hormone levels. 25 cases were treated with prednisone, 23 cases were treated with intrathyroid injection of dexamethasone, 23 cases were treated with intrathyroid injection of dexamethasone and triamcinolone, all recovered well, and 5 cases underwent operation incorrectly. Conclusions Confirmation of subacute thyroiditis should put emphasis on a complete medical history, physical examination and necessary tests. Nuclear medicine tests play an important role in diagnosis of subacute thyroiditis, and the diagnostic drug treatment or fine needle aspiration biopsy may be performed in suspected cases. Glucocorticoid is the best medicine for treating this kind of disease. There is no need for operation therapy of subacute thyroiditis.