Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. The study aimed to evaluate the diagnostic accuracy of intraoperative intact parathyroid hormone (IO-iPTH) in patients with secondary hyperparathyroidism (HPT). The cut-off for IO-iPTH monitoring remains unknown. This was a single-center retrospective review of 226 consecutive patients (107 males and 119 females) who underwent parathyroidectomy for secondary HPT between May 2010 and March 2014. The predetermined cut-off for IO-iPTH was a 70%IO-iPTH drop from baseline 10minutes after total parathyroidectomy and thymectomy. We used 60 pg/mL iPTH value on postoperative day 1 (POD1) as an indicator of successful removal of parathyroid glands and reviewed the frequency of reoperation other than in autografted sites during the observation period. This study was based on the Standards for the Reporting of Diagnositic accuracy compliant. The reoperation rate in patients with 60 pg/mL iPTH value (POD1) was significantly higher than that in patients with 60 pg/ mL iPTH value (POD1), (13.0%versus 0.5%P=0.003). Sensitivity, specificity, and accuracy of 70%IO-iPTH drop were 97.5%, 52.2%, and 92.9%, respectively, this criterion was demonstrated to be beneficial in 26 patients. In 5 patients, 70%IO-iPTH drop was observed and further exploration enabled sufficient removal of parathyroid glands. In 21 patients, although fewer than 4 parathyroid glands were removed after enough explorations, 70%IO-iPTH drop enabled termination of operations and iPTH value (POD1) was 60 pg/mL. An iPTH value of 60 pg/mL (POD1) was a good predictor for successful parathyroidectomy. A 70%IO-iPTH drop from the baseline was appropriate to determine sufficient parathyroid gland removal during parathyroidectomy for patients with secondary HPT.