The post-operative effects of maxillary le Fort I osteotomies on tooth sensibility and recovery of maxillary sinus integrity has been studied in thirty patients. The results show that tooth sensibility is lost in over 90% of the teeth post-operatively but gradually returns by 18 months in almost all of the teeth. Radiographic examination of the maxillary sinus post-operatively shows total or almost total radiopacity in all patients whereas later controls at 2 months and 6 months show normalisation of the bony and soft tissue structures in over 55% of the patients. At 6 months some of the patients (30%) show latent mucosal borderline swelling either bilateral or unilateral. A certain remodelling of the maxillary sinus was seen in all patients.