A 69-year-old man visited in the department of ophthalmology of this university, complained with exophthalmos. He was pointed out hypercalcemia and transferred to the department of endocrinology. The chest X-ray and thoracic CT showed a large mass in lower lobe of the left lung. Cytological diagnosis of this tumor was squamous cell carcinoma. In clinical examination, serum CA was 12.2 mg/dl in spite of normal level of PTH, calcitonin, 1 alpha, -25 (OH) 2D3 and uric cAMP. On the other hand, PTHrP-intact in serum was 9.8 pmol/l. His thyroid gland had no abnormality in palpation or roentogenological examination. The thyroid functions, thyroglobulin, thyrotropin receptor antibody, thyroid test and microsome test were all in normal limit. From these results, he was diagnosed of lung cancer with humoral hypercalcemia of malignancy and euthyroid "isolated" Graves' ophthalmopathy. Left lower lobectomy with mediastinal lymph node dissection (R 2 a) was done and p-stage was IIIA. After operation, serum Ca decreased in normal level and the exophthalmos was also improved gradually. He was in well until 10 months after operation, and died with multiple lung metastases and hypercalcemia. Exophthalmos was also recurred in his terminal stage. Similar case could not find in literature and some discussion of the literatures was mentioned.