The lingual foramen in the midline of the mandible causes confusion in terminology, incidence of occurrence and contents. A survey of 314 dried mandibles showed the foramen to be present in 311 specimens (99.04%). Sectioning of cadaver specimens illustrated a canal traversing the bone to approximately 50% of the buccolingual dimension of the mandible. The contents of the foramen were found to be an artery, which was an anastomosis of the sublingual branches of the right and left lingual arteries. Wire markers were placed in the foramen and the genial tubercles were covered with lead foil to illustrate the radiographic relationship between them. The radio-opacity peripheral to the foramen as seen on a radiograph is produced by the wall of the canal and not the genial tubercles as previously reported. While the foramen is not seen on many radiographs of the lower incisor region, this can be accounted for by a change in orientation of the x-ray beam. A pilot study revealed an incidence of 49% of the lingual foramen on periapical radiographs of the mandibular incisor region in an adult population, the previous reported incidence being 28%.