The mediastinal parathyroid cyst is a very rare cause of space occupying lesions in the mediastinum.We report a case of a non-functioning mediastinal parathyroid cyst that occurred ina 42 year-old male. He suffered from foreign body sensation of the throat whenever he wasin the supine position. A chest computed tomography showed a round cyst with a narrowbase attached to trachea. It was white and tan, thin-walled semi-transparent cyst containingyellow and tan serous fluid. Microscopically it was characterized by a thin fibrous wall linedwith a single or double layer of uniform cells with clear cytoplasm and small nuclei. The liningcells were immunopositive for chromogranin A.