A 32-year-old man had a giant cervical mass, dysphagia, dyspnea, and severe hypercalcemia. A computed tomographic scan showed the mass to extend from the left mandible to the level of the aortic arch. Exploratory surgery of the neck revealed a ruptured parathyroid cyst complicated by massive hemorrhage into the cervical tissues and mediastinum. The postoperative course was uncomplicated with prompt resolution of the hypercalcemia. Although a rare occurrence, extracapsular parathyroid hemorrhage should be considered in the differential diagnosis of all rapidly evolving cervical and mediastinal masses, especially when hypercalcemia is present.