Parathyroid carcinoma is a rare tumor and its clinical course is variable. Differentiation of patients with parathyroid carcinoma from those with parathyroid adenoma is often difficult both preoperatively and at operation. For good results, the surgeon must recognize this disorder and perform an en bloc resection at the initial surgery. A neck dissection is necessary only when there is evidence of regional node metastases. After surgery, periodic follow-up of the serum calcium and iPTH levels is essential. When hypercalcemia recurs or the serum iPTH increases, localization studies with the use of thallium-201 scanning help detect local recurrence and regional lymph node metastases, but unfortunately, this method often fails to localize pulmonary metastases. Chest radiographs and CT scanning are useful for delineating pulmonary metastases. A wide excision of locally recurrent tumor, an en bloc radical neck dissection and mediastinum dissection for lymphatic metastases, and an aggressive surgical resection of lung metastases are recommended. Although these operations are rarely curative, they usually offer definite palliation of the marked hypercalcemia, often for a considerable period. Drugs to lower the serum calcium level and systemic chemotherapy are currently of only limited benefit, and radiation therapy is generally ineffective.