The position of the lingual nerve in the mandibular third molar region was measured and documented in 68 cadaver dissections (34 adult cadaver heads). In 8.8% of the dissections, the lingual nerve was found at or above the level of the alveolar crest. In the horizontal plane, the nerve contacted the lingual plate of the third molar in 57.4% of the specimens. There was also a significant relationship between the degree of mandibular crest atrophy and the distance from the nerve to the molar region. The distance decreased with the degree of atrophy. There was no significant difference between the two sides of the head. These results demonstrate the vulnerability of the lingual nerve as it medially passes the mandibular third molar and may help avoid lingual damage during surgery in the third molar and retromolar region of the mandible.