Primary hyperparathyroidism is rare disease entity which secretes parathyroid hormone in excessively resulting in hypercalcemia. It involves skeletal system, urinary tract, gastrointestinal tract, and central nervous system. Recently the determination of the serum calcium and parathyroid hormone level has become a routine laboratory test and the localization of involved gland by neck ultrasonogram and parathyroid gland substraction scan has reduced operative complications. For the purpose of improvement of diagnosis and treatment, the authors analyzed the clinical characteristics of 6 cases of primary hyperparathyroidism(adenoma 5 cases, carcinoma 1 case) during 10 years and report with literatures.