A 99mTc-sestamibi scan has become the most widely used localizing test for identifying a parathyroid adenoma. Despite its popularity, the effectiveness of 99mTc-sestamibi scan for parathyroid localization is still controversial due to the large number of false-positive results. The false positive 99mTc- sestamibi scan can be attributed to a thyroid adenoma, nodular hyperplasia, metastatic thyroid cancer and other proliferating thyroid diseases because 99mTc-sestamibi is specific to the mitochondrial membrane of cells with high-level metabolic status, and not specific to the parathyroid itself. Minimally invasive radio-guided parathyroidectomy (MIRGP) was performed on a 61 year-old woman. The 99mTc-sestamibi focus was completely excised with γ-probe guidance. However, the frozen pathology showed the excised tissue to be a thyroid papillary carcinoma. We present the unexpected false-positive 99mTc-sestamibi in MIRGP, and discuss the considerations in order to reduce the number of false- positive parathyroid 99mTc-sestamibi scans.