Aim and objective: To evaluate the incidence of various locations of enlarged eutopic and ectopic parathyroids in patients of hyperparathyroidism, their imaging features, diagnosis, and surgical confirmation. Materials and methods: A retrospective study conducted at a tertiary institution, where 400 patients operated for hyperparathyroidism from 2012 to 2017 was analyzed. Diagnostic findings of Tc-99m-sestamibi scan and ultrasound were compared with surgical findings and subsequent histopathology. Contrast CT(4D CT) was utilized only in select cases. Results: Of 400 patients single adenoma was seen in 350 patients (87.5%), two or more nodules in 41 patients (10.2%), and carcinoma in 3 cases. Of the 350 solitary adenomas, 291 were juxtaposed to thyroid (83.1%), and ectopic in 59 (16.8%) cases. Ectopic along the thymic tract in 38 cases (10.8%), upper mediastinum 8 cases (2.2%), angle of jaw in 2 cases (0.5%), carotid sheath 2 cases (0.5 %), retroesophageal 2 cases (0.5%) and intrathyroidal in 7 cases (2%). Tc-99m-sestamibi scan was positive in localizing parathyroid nodules in 297 (84.8%) cases, and ultrasound in 339 (96.8%) cases. Of the nodules localized by Tc-99m-sestamibi scan, 82% were true and 3% were false localization at the surgery. Nodules localized by ultrasound were true in 99% and false in 1% cases. Ultrasound localized the nodules in sestamibi negative cases in 12% of patients. Conclusion: Identification of enlarged parathyroids and their differentiation from thyroid nodules and other neck lesions is the key role of imaging. Ultrasound is complimentary to Tc-99m-sestamibi scan and offers significant value addition by precision anatomical localization, characterization and finding additional nodules. Using two imaging modalities of Tc-99m-sestamibi scan and ultrasound, the diagnostic sensitivity is 99% and specificity is 98%. Clinical significance: Localization of all the abnormal parathyroid glands in hyperparathyroidism remains a diagnostic challenge on account of both sensitivity and specificity of the available imaging modalities, as well as anatomical variations in the location of the parathyroid glands. A thorough knowledge of the anatomy, embryology along with the merits and pitfalls of the various available imaging modalities is essential to make an accurate preoperative diagnosis and avoid revision surgeries. Keypoints: • Parathyroid glands are ectopic in 16.8% cases. • Technetium Tc-99m-sestamibi localizes the parathyroid nodules in 85% cases. • Ultrasound detects parathyroid nodules in additional sestamibi negative cases (12%). • Ultrasound gives precise anatomical localization of parathyroid nodules. • With both MIBI and ultrasound, the diagnostic sensitivity is 99% and specificity is 98%.