Clinical data: a 60-year-old woman was referred for an evaluation of hyperthyroidism. She was treated with Graves' disease for 11 years. Her complaints recurred 3 months before the present examination. She had thyroid associated orbitopathy including diplopia.

Palpation: diffusely enlarged thyroids.

Result of blood test: hyperthyroidism with TSH-level 0.001 mIU/L and FT4 71.8 pM/L.

Ultrasonography: a hypoechogenic, inhomogeneous thyroid was found with increased vascularization.

Clinical diagnosis: recurrent hyperthyroidism caused by Graves-Basedow's disease.

Comment: daily 40 mg methimazole was administered. 2 months later the FT4 level became normal. Surgery was advised because of TAO.

Histopathology: diffuse goiter corresponding to Graves' disease.