Aim: To study the longitudinal effect on the dentition and facial morphology of children suffering from obstructive sleep apnea syndrome and enlarged tonsils who have been tonsillectomized to relieve the pharyngeal obstruction. Material and Methods: The mean age of the 14 children in the experimental group was 5.7 years; there were matched controls without pharyngeal obstruction problems. Preoperative, 1-year postoperative, and 3-year postoperative analyses of several dentitional, facial, and breathing variables were done. Results: Significant differences for several dentitional and facial variables were shown, despite the small number of children and the short observation time. The largest changes occurred during the first postoperative year, indicating that the obstruction of the airway had significantly impacted facial morphology and the dentition in young children. Conclusion: Normalization after relief of the obstruction occurred mostly during the first postoperative year. World J Orthod 2002;3:67–72.