Bilateral neck exploration, the identification of all parathyroid glands and removal of all abnormal glands, has traditionally been regarded as the standard surgical strategy for the treatment of primary hyperparathyroidism (pHPT) [1][2][3][4]. However, in recent years, several investigators have questioned the routine performance of bilateral neck exploration because the cause of pHPT in most patients is a single parathyroid adenoma and preoperative imaging tests, such as Technetium-99m sestamibi scans and ultrasound examination have enabled precise localization of the affected parathyroid gland with high sensitivity [5][6][7]. Use of intraoperative PTH (IOPTH) measurement or the gamma probe with perioperative sestamibi injection has also contributed to improving results A group who underwent surgery without IOPTH monitoring (Group 1; n=87), and a group who underwent surgery with IOPTH monitoring (Group 2; n=80), in which IOPTH was measured at 5, 10, 15 minutes after excision of the abnormal parathyroid gland. Criterion for evaluation as a cure was a drop in intact PTH level of 50% or more from the preoperative baseline value. The overall cure rate in Group 1 was 93.1%. An enlarged parathyroid gland that was consistent with the results of a preoperative imaging study was found in 84 patients (96.6%). The overall cure rate in Group 2 was 97.5%. In 7 of the patients, there was no drop of 50% or more at any of the 3 points in time measured. Two of these patients were found to have had double adenomas, one on each side, during the initial surgery. Three others were eucalcemic and had normal intact PTH values after surgery, and the remaining 2 patients had persistent disease. Although preoperative localization studies are accurate and essential, IOPTH monitoring improves the cure rate of minimally invasive parathyroidectomy. IOPTH monitoring is a valuable adjunct to achieve adequate intraoperative decision-making, recognizing and resecting additional image-negative hyperfunctioning lesions.