Apert syndrome carries a characteristic phenotype of midface hypoplasia, syndactyly, craniosynostosis, and developmental delay. These patients frequently require a large number of surgical procedures to produce a functional and aesthetically pleasing correction of their facial deformities. Although most of the focus for surgical planning is allocated to the cranial vault and the midface, controversy exists as to whether the mandible is intrinsically abnormal in this population.A retrospective chart review was performed to identify patients with Apert syndrome cared for at The Children's Hospital of Philadelphia. Patients with available craniofacial computed tomographic scans after skeletal maturity were examined using cephalometric and three-dimensional volumetric techniques. A comparison was made to age- and demographically matched controls, and statistical significance was determined using the Student t test (P < 0.05).Thirty-eight patients, in total, were identified, 9 of which had available three-dimensional computed tomographic scans. Most patients underwent frontal-orbital advancement in their infancy and at least 1 midface procedure later in life. Three-dimensional volumetric analysis identified a decreased maxillary volume (P = 0.03) in the population with Apert syndrome but found no difference in the mandibular volume (P = 0.59). Cephalometric analysis demonstrated that the patients with Apert syndrome have normal ramal height but a statistically significant decreased mandibular length.The mandible with Apert syndrome seems to be intrinsically normal on the basis of our three-dimensional analysis, and differences in appreciated mandibular length are likely related to the interrelationship with the maxilla. Patients can therefore be instructed that improving the midface position may likely also reduce the compensatory mandibular deformity.