Abstract: Objective To analyze the diagnostic value of⁹⁹Tc^m-sestamibi (MIBI) double phase scintigraphy in patients with hyperparathyroidism. Methods The clinical data of 73 patients with hyperparathyroidism confirmed by surgery pathology were retrospective analyzed.⁹⁹Tc^m-MIBI double phase scintigraphy was performed and whole body scan,computerized tomography (CT) or single photon emission computerized tomography/computerized tomography (SPECT/CT) were carried out when necessary.Serum calcium (Ca) and phosphorus (P) were measured for all patients before and after operation.Serum parathyroid hormone level was determined before operation and in most of patients in one week post-operation. Results Twenty-nine cases of patients were primary parathyroid hyperthyroidism who undertook⁹⁹Tc^m-MIBI double phase scintigraphy,28 lesions were detected.Thirty-one lesions were found in pathology,28 were hyperplasia parathyroid adenoma and 3 were parathyroid hyperplasia.The sensitivity of⁹⁹Tc^m-MIBI imaging for primary hyperparathyroidism lesions diagnosis was 90.3%(28/31).In 44 cases with secondary parathyroid function hyperthyroidism,there were 154 lesions with parathyroid hyperplasia confirmed by pathology,and 118 lesions were detected by⁹⁹Tc^m-MIBI imaging.The sensitivity for parathyroid hyperplasia diagnosis was 76.6%(118/154).In parathyroid adenoma with positive imaging,most of the tumors were clearly visualized with intensely radioactive concentration in tumor,and most patients characterized by hypercalcemia and hypophosphatemia.While in patients with parathyroid hyperplasia the radioactive concentration in hyperplastic tissue was mild and far lower than that in parathyroid adenoma.Although,there was not obvious increasing of serum calcium,significantly elevated serum phosphorus was observed in patients with parathyroid hyperplasia.However,in both of patients with parathyroid adenoma and parathyroid hyperplasia,the level of serum parathyroid hormone was decreased after operation in one week. Conclusion ⁹⁹Tc^m-MIBI had higher diagnosis sensitivity in parathyroid adenoma than parathyroid hyperplasia,and it's helpful in the discovery of ectopic parathyroid tissue and its preoperative localization.