The complex rotation process of the mandible during growth is elucidated by longitudinal roentgencephalometric analyses, using metallic implants as fixed references. Contrasting development of face and mandibular shape is described in three subjects. In the so-called long face syndrome, development is characterized by increasing inclination of the mandible during growth with only moderate remodeling. In the subjects with juvenile rheumatoid polyarthritis and mandibulofacial dysostosis, the increase in mandibular inclination is moderate. However, the mandibular corpus rotates backward to an extreme extent within the more stable soft tissue matrix, giving rise to the characteristic development of angular notching with an extended angular process at the lower border.