The parathyroid carcinoma is a rare cause of primary hyperparathyroidism. There was approximately 170 reports in the would literature. and only two documented cases in Korean literature. It is still difficult to distinguish. histologically, benign from malignant parathyroid tumors. However, if diagnotic criteria are that strict, it can be suscessfully cured by initial operation. The initial operation should be an en bloc resection of the tumor, avoiding rupture of the tumor capsule and spillage of tumor cells. This report details the management of a 51 year old female with functioning parathyroid carcinoma who underwent an en bloc resection of the tumor at the time of initial operation.