Goiter is present in 25-50% of patients with acromegaly, which probably results from IGF- I stimulation of thyroid cell growth. These goiters are usually non-toxic but there have been well documented cases of co-existent hyperthyroidism and acromegaly. Graves disease with acromegaly has been rarely reported compared with the other type of hyperthyroidism due to increased tumoral secretion of TSH. We experienced a 44-year-old woman who presented with Graves disease and acromegaly. Basal serum GH and IGF-I concentrations were 10.8 pg/L and 571.82 ng/mL, respectively (reference value: (5 mg/L and 130-354 ng/mL, respectively). GH was not suppressed less than 2 pg/L during oral glucose loading test. GH was stimulated by TRH. Postcontrast sellar MRI demonstrated ovoid-shaped low signal intensity nodule measuring O.8 cm in diameter in left side of pituitary gland. Thyroid scan(131I) showed enlarged thyroid with increased radioiodine uptake (61.3%). Histologic examination showed acidophilic adenoma. GH and prolactin were positive on immunohistochemical staining. GH was suppressed less than 2.26 mg/L by oral glucose loading following operation. The patient has been followed with antithyroid drug(PTU) medication after operation(TSA).