The obstructive sleep apnea syndrome is an important and prevalent cause of sleep disorder with serious physical and social consequences, if not treated. The clinical exam is insuficient to confirm the diagnose, demanding complementary exams: fiber optic nasofaringoscopy with Miller maneuver;cefalometry, mainly in patients with skeletal abnormalities and Polissonography, which is the most important to this evaluation. The maxillo-mandibular osteotomy is showing promissing results to the cure of SAOS without sucess with other treatments. This study presents a review of literature about SAOS and reports a case of a patient having Treacher-Collins Syndrome; mandibular advance was opted because of possibility of simultaneous correction of funcional and esthetic abnormalities.