Crouzon and Apert syndromes have been reported to be associated with mutations in Fibroblast Growth Factor Receptor 2 (FGFR2) gene in various ethnic groups, but never in Southeast Asian subjects. Therefore, the authors conducted a study to characterize 11 Thai patients: four with Crouzon syndrome and seven with Apert syndrome. All cases are sporadic. Mean paternal and maternal ages were 38.7 and 28.6 years, respectively. Molecularly, all patients were found to have mutations in the FGFR2 gene. Three mutations (C278F, S347C, S351C) were detected in all Crouzon patients with two having S351C. The seven patients with Apert syndrome have either S252W or P253R mutation. The authors' findings that sporadic cases were associated with advanced paternal age and that they all had mutations in FGFR2 are consistent with previous reports. This is another observation supporting the causative role of FGFR2 mutations in Crouzon and Apert syndromes.