In recent years obstructive sleep apnea syndrome has gained increasing interest. Treatment of choice is nasal continuous positive airway pressure ventilation during sleep for upper airway patency, which does not cure sleep apnea and has to be applied throughout a patient's lifetime. In respect to various underlying pathomechanisms, in certain cases with craniofacial disorders, causal therapy by craniofacial osteotomies seems possible. A series of 21 consecutive patients with maxillary and mandibular deficiency were treated primarily with a 10-mm maxillomandibular advancement by retromolar sagittal split osteotomy and Le Fort-I osteotomy, respectively. Obstructive sleep apnea syndrome was considerably improved in all patients. In 20 of 21 patients, the postoperative respiratory disturbance index (RDI) was reduced clearly to under 10, oxygen saturation rose and sleep quality improved. This was achieved by a maxillomandibular advancement of 10 mm without secondary refinements. In one patient the RDI could only be reduced to 20, probably due to insufficient maxillary advancement; oxygen desaturations still existed despite secondary corrections. These results indicate that successful surgical treatment is possible in a high percentage of selected patients with certain craniofacial characteristics. In addition to cardiorespiratory polysomnography there should be routine cephalometric evaluation of all patients. Maxillomandibular advancement should be offered as an alternative therapy to all patients with maxillary and/or mandibular deficiency or dolichofacial type in combination with narrow posterior airway space.