With an estimated incidence of 0.015 per 100,000 people and an estimated prevalence of 0.005% in the USA, parathyroid carcinoma is one of the rarest of all human cancers. The etiology of parathyroid carcinoma is unknown. Parathyroid carcinomas are typically slow-growing tumors. They have a tendency to recur locally and metastasis occurs late. Ninety-five percent of parathyroid carcinomas are functioning tumors and they secrete parathyroid hormone (PTH). Surgery is the only potentially curative treatment for parathyroid carcinoma. Early surgery at a point when extensive local invasion and distal metastases are less likely is the most important factor for optimal outcome. For these reasons, both preoperative suspicion and intraoperative recognition of the malignant nature of the tumor are of paramount importance. Endoscopic, video-assisted, radioguided, and every recently introduced minimally invasive parathyroidectomy techniques are absolutely contraindicated. Traditional cervicotomy is strongly recommended when approaching a parathyroid mass suspicious for carcinoma. This chapter describes workup and surgical approaches and eludes nonsurgical therapeutic strategies as well.