Le Fort III distraction osteogenesis may be indicated in the treatment of syndromic craniosynostosis with severe midface retrusion and proptosis. This study assesses the stability of proptosis correction over 10-years.A retrospective review identified 15 patients with syndromic craniosynostosis treated by Le Fort III distraction prior to age 10 (9 males, 6 females; age 4.9 ± 1.5 years). Untreated, non-craniosynostotic age- and gender-matched controls were obtained from historical growth records. Lateral cephalometric tracings at pre-surgery (T1), immediate (T2), 1 year (T3), 5 years (T4), and 10 years (T5) (n = 11) post-distraction were superimposed using the best-fit of cranial base. Proptosis severity was defined as the horizontal distance between the Ant. Globe cephalometric point and orbital rim landmarks Orbitale and Lat. Orbit.The orbital rim advanced 10.54 ± 3.78 mm (P < 0.001) at Orbitale and 9.73 ± 4.54 mm (P > 0.001) at Lat. Orbit from T1 to T2; Ant. Globe advanced 3.13 ± 3.02 mm (p 0.001). Proptosis decreased 7.41 ± 5.29 mm (P < .001) from Orbitale and 6.60 ± 6.50 mm (p 0.002) from Lat. Orbit. Comparison to controls demonstrated phenotypic correction. In craniosynostotic patients from T2 to T5, the bony orbital rim demonstrated non-significant remodeling posteriorly and inferiorly. Anterior Globe moved 3.79 ± 1.47 mm anteriorly (P < .001), which did not differ significantly from controls. Proptosis increased by 4.18 ± 2.94 mm in craniosynostotic patients from T2 to T5.Le Fort III distraction was stable, with no significant anteroposterior relapse of the maxilla or bony orbit. Phenotypic relapse of proptosis to pre-treatment levels occurred through deficient growth of the midface, surface resorption at the orbital rim, and preservation of normal forward movement of Ant. Globe.