PURPOSE: The improvement of intraoperative parathyroid hormone (IOPTH) assay and localization studies has enabled a minimally invasive parathyroidectomy (MIP) in primary hyperparathyroidism (pHPT). The aim of this study is to analyze the demographics, clinical presentations, and surgical outcomes of the pHPT patients who received surgical management with versus without IOPTH. METHODS: Analysis of a database was performed on 53 patients who underwent parathyroidectomy for pHPT from 2004 to 2013. Preoperative localization was done by both sestamibi scan and ultrasonography. We divided the patients into two groups (without IOPTH versus with IOPTH) and analyzed the surgical outcomes statistically between two groups. RESULTS: The concordance rate of Technetium 99m sestamibi scan and ultrasonography was 73.6% and 90.6%, respectively. The overall cure rate of group 1 (without IOPTH) was 94.9% and that of group 2 (with IOPTH) was 100%. The decline of PTH at postoperative 5 minutes and 10 minutes was 75.2% +/- 14.9% and 84.9% +/- 8.6% in cured patients. On the other hand, that of noncured patients at 5 minutes and 10 minutes was 17.2% +/- 9.7% and 8.2% +/- 2.2%. There was a significant difference in the drop rate of IOPTH between cured and persistent patients (P < 0.01). Pathological examination showed adenoma in 41 of 53 patients (77.4%) and hyperplasia in 10 of 53 patients (18.9%). CONCLUSION: Even though the localization studies were successful, IOPTH monitoring is essential to avoid a surgical failure in MIP.