Parathyroid cysts are uncommon causes of neck or mediastinal masses. They have been mistaken for cystic thyroid nodules, brachial cleft cysts, or thyroglossal duct cysts. Two types of parathyroid cysts have been recognized; the non- functioning forms, which are more frequent and the functioning paratyroid cysts, which are rarer and cause hyperparathyroidism. Parathyroid cysts are usually located in the inferior parathyroid gland, which are most commonly involved with a left-sides predominance. Although their location in mediastinum has also been described. Parathyroid cysts may present as a diagnostic problem. It is sometimes difficult that parathyroid lesions are distinguished from thyroid ones with current imaging techniques. Diagnosis is based on the histopathological appearance of the cyst and PTH level in the cystic fluid. Percutaneous needle aspiration of parathyroid cysts reveals crystal clear fluid. Elevated PTH levels in the cystic fluid confirms the diagnosis. The presence of parathyroid tissue within the cyst wall is diagnostic. Nonfunctioning cyst may be treated with aspiration alone, surgical excision is indicated for functioning cyst. We present the case of two patients with a parathyroid cyst.