Adenomatoid odontogenic tumors are rare in the molar region and occur most commonly in the anterior jaw. This report describes the clinical and histological findings of an adenomatoid odontogenic tumor associated with the lower first molar. A healthy 21-yearold woman was referred to our department for a painless bony swelling on the right side of the mandible. Radiographic examination showed a well-circumscribed cystic lesion surrounding the crown of a molar like impacted tooth and an irregular intralesional radiopacity.<BR>Under general anesthesia the cystic tumor was enucleated along with the impacted tooth. The extracted tooth was morphologically identified as the lower right first molar by the presence of five cusps and three roots and by the fact that a tooth had not erupted at the site of the lower first molar. Histological examination revealed advanced calcification and proliferation of spindle-shaped and polygonal tumor cells containing eosinophilic and PASpositive droplets between the intercellular spaces. Despite the lack of duct-like structures, the overall histological features confirmed the diagnosis of an adenomatoid odontogenic tumor. Four years four months after the operation there have been no signs of recurrence.