Objectives: To review minimally invasive parathyroidectomy (MIP) in patients undergoing initial surgical management of primary hyperparathyroidism (HPT) with preoperative, localizing sestamibi scanning (MIBI), and concordant ultrasonography (US) to determine if intraoperative parathyroid hormone (iPTH) is necessary in these cases. Minimally invasive parathyroidectomy has become an acceptable therapeutic option in treating primary HPT. Preoperative MIBI scanning, high-resolution US with color Doppler flow, and iPTH monitoring have refined this technique. Design: Retrospective review. Patients: The medical records of 738 consecutive patients who had undergone surgery for HPT. After excluding revision surgical procedures, secondary and tertiary HPT, unavailable intraoperative parathyroid (PTH) data, concomitant thyroid disease requiring thyroidectomy, and patients without preoperative MIBI or US, 428 patients (58%) were included in the study. Results: The mean decrease in PTH level was 85%. Of the 428 patients with primary HPT included in the study, 209 patients (49%) had localizing, concordant preoperative MIBI and US. A decline of more than 50% in iPTH levels was observed in 202 patients (97%) after removal of parathyroid tissue localized by MIBI and US. The procedures for 4 patients were converted to bilateral neck explorations after the postexcision PTH level failed to drop less than 50%. Conclusions: Our results show that iPTH monitoring may be eliminated in MIP surgery in a carefully selected group of patientswhohave preoperative, localizing MIBI with concordant US. This potentially allows an increase in operating room efficiency and a decrease in costs while performing MIP. ©2009 American Medical Association. All rights reserved.