Surgery is a major modality in the treatment of obstructive sleep apnea syndrome (OSAS), and maxillomandibular advancement (MMA) has been shown to be the most effective surgical option. However, despite the successful short-term (6-9 months) results reported by various investigators, little is known of the long-term clinical outcomes. A review of our long-term clinical results demonstrated that MMA achieves long-term cure in most patients. Aging and minor weight gain did not appear to have a significant adverse effect on the long-term results; however, major weight gain did seem to have a significant negative impact on the long-term outcomes. Therefore, long-term follow-up with proper counseling on weight maintenance or reduction is essential in improving long-term results.