Parathyroid carcinoma is a rare cause of hyperparathyroidism. Its prognosis is mainly related to an en-bloc resection of the tumor and of the involved structures. However because of the small number of cases reported in the international literature, biological behaviour of the disease is not well known. In this report we describe one case of parathyroid carcinoma seen in our Institution. Preoperative presumption of parathyroid carcinoma thanks to clinical features and ultrasound imaging helped us in deciding an adequate surgical resection.