Pathologic migration is an abnormal change in the position of a tooth within the dental arch. There are many etiologic factors associated with this phenomenon, but the exact cause is often difficult to diagnose. The following is a report of a 42-year-old man exhibiting a unique form of bilateral migration of his mandibular third molars. He was asymptomatic and unaware of this occurrence. The morbidity to remove these teeth was deemed too great to justify extraction. Biopsy of the overlying tissue associated with a left-impacted third molar revealed no significant pathologic process other than inflammation and some hyperplasia within the dental follicle. Histologic-radiographic correlation was inconclusive in determining whether epithelium from pericoronal soft tissue involving the right third molar was from a hyperplastic dental follicle or a small dentigerous cyst. It is speculated that the ultimate cause of the migration of the third molars was severe, aggressive periodontal disease of the adjacent molars.