Background and Objectives : Parathyroid adenoma is a rare disease in Korea, but the incidence of parathyroid adenoma has gradually increased due to generalized measurement of serum calcium and imaging study according to wide spread public health screening program. In previous researches, the analysis of clinical aspects were insufficient due to a few cases. The purpose of this study was to assess the clinical analysis of surgically treated parathyroid adenoma with hyperparathyroidism. Methods : We reviewed the medical records of nineteen cases of parathyroid adenoma with hyperparathyroidism. Initial symptom to visit hospital, hypercalcemia associated medical symptom, surgical outcome and complication were investigated. Serum total calcium, parathyroid hormone, phosphate, alkaline phosphatase were checked before and after surgery. Imaging study was performed with combination of radionuclide parathyroid scan, ultrasonography and neck CT scan. Results : The initial symptoms were no symptom(6/19), pelvic pain(5/19), muscular weakness (3/19), bone pain(3/19) and palpable neck mass(2/19) in order of frequency. Serum total calcium, parathyroid hormone decreased and phosphate increased after surgery than before surgery statistically significantly. Sensitivities of parathyroid scan, neck ultrasonography and neck CT as preoperative localization test were 88.2%, 72.7%, 73.3% each. The most common postoperative complication was transient hypocalcemia(9/19). Conclusion : Similar to previous study, parathyroid adenomas have numerous clinical features and surgical treatment via unilateral approach with preoperatively localized single parathyroid adenoma was successful. In our study, parathyroid adenoma was predominantly detected by elevated serum calcium level with no clinical symptom so we need to evaluate parathyroid adenoma, if serum calcium elevated.