Cysts of the minor salivary glands are common, but that of the parotid glands are rate. A case of cyst of the parotid gland in a 13-year-old girl was present. The patient was referred to our clinic by her doctor because of massive painless swelling in the right side of the parotid area. Mechanical trauma, laceration, chronic obstruction due to stricture, and the presence of a sialolith and chronic sialoadenitis can account for the formation of parotid retention cysts in same cases. In this case, no obvious etiologic factor (s) could be determined, but calculus of Stensen's duct was suspected. The mass was removed surgically, and the histopathological diagnosis was a retention cyst of the parotid gland. No evidence of recurrence was observed up to date.