Amelogenesis imperfecta (AI) is a group of hereditary disorders whose manifestations are generally considered as being confined to the teeth. Pedigree analysis of a kindred revealed 2 siblings affected with AI which was consistent with an autosomal recessive mode of inheritance. Cephalometric evaluation showed both children to have an obtuse gonial angle and steep mandibular plane. These skeletal changes were manifested as a severe anterior open bite. Histological evaluation of the teeth demonstrated numerous enamel changes including altered prism morphology, prism coalescence and disruption, globular inclusions, and irregular crystallite orientation. The clinical and histological data are consistent with autosomal recessive pigmented hypomaturation amelogenesis imperfecta. The enamel defects appear to be caused by the combination of decreased mineral deposition with abnormal crystallite and prism formation. Some areas of enamel hypoplasia seem to exist as well.