Primary hyperparathyroidism is still uncommomn disease in Korea. However the frequency of this disease has been slowly increased with routine measurement of serum calcium and increasing awareness of hyperparathyroidism in recent years. The diagnosis is established by a persistent elevation of serum calcium and parathyroid hormone and by clinical evaluation. This is a report of eleven patients with primary hyperparathyroidism treated with surgical operation during a period from 1983 to 1997 at Department of Hospital. Authors analyzed the cases to evaluate clinical characteristics and outcome of surgical treatment retrospectively. The result was as follows. 1) In sex distribution, female patients were eight and three were male, the age distribution ranged from 18 to 67 years. 2) The presenting clinical manifestations were renal and urinary stone in eight, bone pain or fracture in six, muscle weakness in four, neurologic symptoms in four, neck mass in three, hypertension in two, and G-I symptoms in one. 3) All patients showed hypercalcemia and elevated serum parathyroid hormone level. 4) Preoperative localization study was performed with computerized tomography, ultrasonography, MRI, arteriography and thyroid scaning. 5) The tumor locations were left lower in eight, left upper in one, right lower in one, and right upper location was one case. 6) Histopathologic findings disclosed adenoma in all cases. 7) All patients were treated by surgical excision and postoperatively transient hypocalcemia occurred in six patients, but no other complication was developed.