Objective: To evaluate vertical and sagittal facial growth in children with Apert and Crouzon syndromes and compare it to the growth patterns of a nonsyndromic control group. Design: Case-control study. Setting: Department of Orthodontics, Children's Hospital Erasmus Medical Centre, Sophia, Rotterdam, The Netherlands. Patients, Participants: Sixty-two patients (37 patients with Crouzon syndrome and 25 patients with Apert syndrome) born between 1971 and 2001 (age range 3.9 to 32 years) and 482 nonsyndromic children as a control group. Interventions: Lateral cephalograms performed prior to any midfacial surgery of 62 patients and 482 nonsyndromic children were traced and horizontal and vertical measurements were digitized. Main Outcome Measures: Cephalometric measurements of SNA, SNB, ANB, NSMe, and SN/palatal plane angles and lower facial height ratio. Results: Horizontal measurements for the syndromic groups showed no change in SNA angle during growth. SNA angles were lower in patients with Apert syndrome compared to patients with Crouzon syndrome. The syndromic groups showed smaller values for ANB angles compared to the nonsyndromic group. Vertical measurements showed increased lower facial height ratios for the syndromic groups compared to control subjects. There was an increasing counterclockwise rotation of the palatal plane in relation t Conclusions: Based on the growth differences identified, the sagittal and vertical jaw relationships differ in patients with Crouzon syndrome, patients with Apert syndrome, and control subjects. Syndromic patients show aggravation of midfacial underdevelopment and anterior rotation of the mandible.