Parathyroid carcinoma is an extremely rare malignant endocrine neoplasm that is very challenging in its diagnosis as well as its treatment. Clinically the disease is detected earlier in patients who present with hyperparathyroidism with signs of profound hypercalcemia. Differentiation between benign and malignant disease of the parathyroid is challenging both for the clinician and for the pathologist. Complete surgical resection at the time of first operation offers the best chance of cure. Even after radical excision which is the standard management, local recurrence and metastases are frequent. The disease usually has a slow indolent course and most patients suffer from complications of hypercalcemia rather than tumor invasion or metastasis. We report a case of a 31-year-old woman who presented with renal colic. Various hematological, biochemical and radiological investigations were performed and a slightly enlarged right parathyroid was found. A clinical diagnosis of parathyroid adenoma was made and a right parathyroidectomy was done. Intraoperatively the surgeon had no suspicion of malignancy but microscopically the lesion was malignant and a final diagnosis of parathyroid carcinoma was rendered based on the criteria of invasion. Since there is no gold standard, a multidisciplinary approach, including the entire clinical, biochemical, radiological and pathological profile of the disease aids in an accurate diagnosis. Here we are reporting a case of a functional parathyroid carcinoma presenting in a relatively young patient with all the biochemical and radiological investigations and intraoperative findings pointing towards a benign parathyroid disease.