Objective: The purpose of this study was to determine whether the incidence of pathologic conditions affecting the pericoronal tissue of unerupted third molars justifies their routine removal. Method and materials: The pericoronal tissue associated with completely unerupted third molars was submitted for histologic examination after surgical tooth removal was performed in 37 males and 55 females, aged 13 to 63 years. The 104 unerupted third molars comprised 68 mandibular third molars (65.38%) and 36 maxillary third molars (34.62%). Results: The incidence of normal tissue of a dental follicle was 41.35%, and the incidence of pathologic tissue was 58.65% (dentigerous cyst, 50.96%; chronic nonspecific inflammatory tissue, 4.81%; odontogenic keratocyst, 1.92%; ameloblastoma, 0.96%). The incidence of pathologic conditions was higher than that of normal conditions in all third molar positions. In younger patients, normal tissue was more commonly found, but in patients older than 20 years, the incidence of pathologic tissue was higher than the incidence of normal tissue. Conclusion: Unerupted third molars should be removed before pathologic changes can occur in their pericoronal tissues. This justifies routine removal of unerupted third molars from patients older than 20 years.