We report a 21-year-old woman with Turner's syndrome, Graves' disease and primary hyperparathyroidism. At 12 years of age, she was of short stature, and was diagnosed with Turner's syndrome and treated with growth hormone. At the age of 17 years, she was diagnosed with Graves' disease. On treatment with methimazole, her laboratory findings normalized. At the age of 20 years, her serum calcium and intact parathyroid hormone levels were high. The upper left parathyroid gland showed swelling and was resected, and adenoma was diagnosed pathologically. Then, primary hyperparathyroidism induced by the adenoma was diagnosed. After the parathyroidectomy, the patient's serum calcium and intact parathyroid hormone levels normalized. Is likely that Turner's syndrome and Graves' disease were not associated with primary hyperparathyroidism. Multiple endocrine neoplasia type 1 was unlikely considering the clinical, laboratory, ultrasonographic, and scintigraphic findings.