An accurate preoperative localization in patients with primary hyperparathyroidism is important for successful surgical intervention . There are many methods for the localization of the primary hyperparathyroidism such as ultrasonography, computerized tomography(CT), magnetic resonance imaging(MRI), angiography and 201T1/99mTc- subtraction scan. Among them 201T1/99mTc subtraction scan in known as the most accurate tool for preoperative localization. Recently 201T1/ 99mTc-Sestamibi has been used for parathyroid gland imaging. We experienced 19 primary hyperparathyroidisms accurately localized with 201T1/99mTc subtraction imaging and Tc-99m- Sestamibi. The sensitivities of the Tc-99m-Sestamibi, 201T1/99mTc subtraction imaging, CT and US were 100%(5/5), 89.5%(17/19) and 61.7(12/19) respectively. With the combination of Tc-99m- Sestamibi and 201T1/99mTc subtraction imaging we could localize with 100% accuracy. Although the case number is small, this study suggests that the Tc-99m-Sestamibi parathyroid scan is very useful and easy to use for preoperative localization in primary hyperparathyroidism.