OBJECTIVE: To present our experience with mediastinal parathyroid cysts and summarize previously reported cases. DESIGN: We retrospectively reviewed medical records and reviewed the pertinent literature. MATERIAL AND METHODS: The clinical, operative, and pathologic findings in 7 cases of mediastinal parathyroid cysts encountered at one institution and 31 cases previously reported in the literature are described. RESULTS: Rarely, cysts may arise from an aberrant mediastinal parathyroid gland. Such cysts may manifest as a symptomatic mass, as an asymptomatic finding on roentgenography, or during the assessment of a patient with hyperparathyroidism. The diagnosis may be made by fine-needle aspiration or by excision and pathologic examination. CONCLUSION: Functioning parathyroid cysts represent degeneration of a hyperfunctioning gland, such as an adenoma, and are usually removed through a cervical approach. Nonfunctioning cysts in asymptomatic patients with normal serum calcium levels are considered indeterminate and should be managed accordingly. Excision is usually recommended.