Introduction: Parathyroid carcinoma (PC) is one of the least common endocrine malignancies seen in <1% of cases of primary hyperparathyroidism (PHPT). The most common presentation is in the form of parathyroid hormone (PTH) dependent hypercalcemia mimicking parathyroid adenoma (PA). However, the hypercalcemia is severe, associated with severe bony manifestations, and often associated with markedly elevated serum PTH. Case series: Our three cases of PC were detected in a single center within a short span of 3 years. All were female between 5th and 7th decade of life. All had initial symptoms of hypercalcemia with a fragility fracture in one. The initial biochemical evaluation showed PTH-dependent hypercalcemia. Two patients had localization of parathyroid swelling on ultrasonography (USG) with confirmation on the sestamibi parathyroid scan. One patient had PA on fine needle aspiration (FNA) of the thyroid nodule. All patients had severe osteoporosis, and one had nephrolithiasis. All had histopathological confirmation of PC postoperatively, but none had metastatic disease. Conclusion: Parathyroid carcinoma (PC) is an extremely rare malignancy that usually presents as PTH-dependent severe hypercalcemia and is often diagnosed postoperatively during histopathology. The most common clues to the diagnosis are markedly elevated serum PTH levels and hypercalcemia of >14 mg/dL.