A case of a large tonsillolith of the left palatine is presented. The lesion was detected incidentally during radiographic examination of a patient presenting with right mandibular pericoronitis. The patient had no symptoms referable to the left tonsillar region. Superimposition of the tonsillolith on the left mandibular ramus on panoramic radiographic examination created the false impression of an intraosseous radiopaque lesion. Many radiopaque structures and lesions occur in the soft tissues close to the jaws and are often observed on panoramic radiographs produced by imaging units with broad focal troughs. Such radiopacities in the mandibular molar-ramus region include sialolith, phlebolith, cysticercosis and calcified lymph node, carotid artery arteriosclerosis, stylohyoid ligament mineralization, and dystrophic calcification in acne scars. Tonsilloliths may present on panoramic radiograph as radiopaque objects superimposed on the midportion of the ascending mandibular ramus, and may be initially misinterpreted as intraosseous lesions of the mandible, such as foreign body, odontoma, sclerosing osteitis, Garre osteomyelitis, fibrous dysplasia, idiopathic osteosclerosis, and osteoma.