The age of closure of skull base synchondroses has never been analyzed in a homogenous population of children with Crouzon syndrome.,A retrospective case-control study was performed on 30 Crouzon children (17 male, 13 female) aged 1 month to 12.48 years with Fibroblast Growth Factor Receptor type 2 mutation. Eleven synchondroses were analyzed on millimetric computed tomodensitometric slices before surgery. Syndromic patients were compared with a series of 235 healthy children previously published.,Synchondrosis closure follows a global pattern that occurs earlier in Crouzon syndrome than in controls (P ≤ 0.002). Synchondrosis fusion starts at 10 months of age with posterior intraoccipital synchondroses and lambdoid sutures, followed by occipitomastoid synchondroses between 1.85 (right) and 2.27 years (left) and anterior intraoccipital synchondroses at approximately 2.80 years. Time to complete fusion varies considerably according to the synchondroses. Spheno-occipital and petro-occipital synchondroses fuse last, at approximately 3 years old.,In children with Crouzon syndrome, synchondrosis closure occurs prematurely, with a time course specific to each synchondrosis.,Copyright © 2017 Elsevier Inc. All rights reserved.