The authors present a clinical analysis of 69 cases of primary hyperparathyroidism during the last 32 years from 1963 to 1994 which were reported in Korean Medical Journals. There were 69 patients, 21 males and 48 females, with a male to female ratio of 1 to 2.3. The age distribution was between 4 months and 65 years. The presenting clinical manifestations were musculoskeletal symptoms (66.7%), renal symptoms (49.3%), and general weakness (21.7%) in that order of frequency. There were 2 patients with asymptomatic hypercalcemia. The mean preoperative serum Ca and P levels were 13.1 mg% and 2.4 mg%. The mean postoperative serum Ca and P levels were 8.0 mg% and 2.7 mg%. The mean preoperative and postoperative PTH levels were 3275 pg/dl (normal range; 220~660 pg/dl) and 392 pg/dl. Preoperative localization was done using ultrasonogram, computed tomogram, thallium-technetium subtraction scan, and arteriogram. Positive localization was made in 84.8% (28/33), 72.7% (24/33), 84.2% (16/19), and 100% (9/9), respectively. In one patient, magnatic resonance imaging was performed and positive localization was made. The location of the lesion was more common in the lower part of thyroid than the upper part and on the left side rather than the right side. There were 7 patients with ectopic locations including the thoracic inlet (2), intrathymus (1), intrathyroidal (1), mediastinum (2), and right subclavicular (1). All patients were treated surgically. The final histopathologic findings were single adenoma in 63, carcinoma in 3, and primary hyperplasia in 2 patients. There was 1 patient with double tumors composed of adenoma and carcinoma.