Extracapsular hemorrhage from spontaneous rupture of a hyperplastic parathyroid gland is exceedingly rare. Rupture of an intrathoracic parathyroid adenoma mimicking a dissecting thoracic aortic aneurysm has been reported in two cases. Hypercalcemic crisis associated with contained hemorrhage within a parathyroid adenoma has been well documented. We present the first reported case of spontaneous rupture and extracapsular hemorrhage of a cervical parathyroid adenoma. Serum calcium levels should be obtained when spontaneous cervical or mediastinal hemorrhage develops without obvious cause.