The location of the mental foramen has often been claimed to be unaffected by alveolar atrophy. In the present study, the distances of the mental foramen and the mandibular canal from the lower cortex of the mandible were compared in a radiographed series of 40 edentulous elderly women with advanced alveolar atrophy and 40 elderly women who had 10 or more lower teeth left. The mental foramen was situated on average 3.8 mm lower in dentulous jaws than in dentulous jaws (P < 0.0001). The mandibular canal was also situated lower in edentulous jaws, but the difference was not statistically significant. The results confirm the finding that the mental foramen seems to descend as a result of alveolar atrophy.