Objective: To evaluate the horizontal migration of the human mental foramen before and after birth. Methods: 54 formalin-fixed fetuses between 17 and 32 weeks of gestation, and 94 panoramic radiographs of children aged between 4 and 12 years were investigated. The distances between the mental foramen and mental symphysis, and the distances between the posterior border of the mandibular ramus and mental foramen were determined according to development periods. Results: Our results confirm that the mental foramen moves in a posterior direction during the development of the mandible. Conclusion: The horizontal location of the pre- and postnatal mental foramen changes in a posterior direction as the development progresses, however, prenatal mental foramen features an irregular behavior, while the postnatal mental foramen gradually migrates posteriorly in a regular pattern. (C) 2011 Elsevier Ireland Ltd. All rights reserved.