Indiana University-Purdue University Indianapolis (IUPUI) / The characteristics of cleidocranial dysplasia were first reported in 1897 by Pierre Marie and Paul Sainton. Since this first classification of the disease, many radiographic and clinical signs have been associated with this entity. Individuals with this disease have been repeatedly described as having a relative prognathism of the mandible due to a small, retropositioned maxilla and an enlarged cranial base. The present study was designed to determine, through the use of cephalometric measurements, if there is truly a difference in the size and position of the maxilla and an enlargement of the cranial base in these affected individuals. Ten cleidocranial dysplasia patients ranging in age from three years to 53 years, and their immediate families were studied. Non-affected members were studied to provide an intrafamilial comparison of skeletal development. The data obtained from the cephalometric measurements showed that the cranial bases for this group were within normal limits, or tending towards the small size. The maxilla was of normal size and the position was normal or anteriorly positioned in all cases. The mandible was considerably larger in 70% of the affecteds studied. Radiographic investigation showed this group to have delayed ossification of cranial sutures and mandibular symphysis. Absent frontal and mastoid sinuses, orbital hypertelorism, osteopetrotic appearance of the cranium, and absent or hypoplastic nasal bones were also observed.