To evaluate long-term clinically significant cephalometric skeletal stability with maxillomandibular advancement (MMA) for obstructive sleep apnea (OSA). We performed a retrospective cohort analysis of long-term clinically significant skeletal stability in patients who underwent MMA for OSA. The primary predictor and outcome variables were the occurrence of and time to loss of clinically significant skeletal stability, respectively, at sella-nasion-B point (SNB).The inclusion criteria included severe OSA (apnea-hypopnea index>30), MMA, diagnostic preoperative and postoperative lateral cephalometric radiographs, and a minimum of 5years of follow-up. Digitized cephalometric radiographs were analyzed at 3 time points: preoperatively, postoperatively, and at last follow-up. Statistical analyses included Kaplan-Meier time-to-loss of clinical stability analysis, the log-rank test, and the Cox proportional hazards model for hazard ratio determination for the influence of the following independent variables on loss of clinical stability: gender, age at the time of surgery, time to follow-up, and amount of surgical movement. Post hoc stratification for bone grafting was completed. Statistical significance was set at the P<.05 level. Thirty consecutive patients with an even gender distribution and average follow-up period of 10.7years were included in this study. Preoperatively, the average age was 43.7years; apnea-hypopnea index, 59.8; and body mass index, 39.3. Half of the cohort had clinically significant loss of skeletal stability at sella-nasion-A point (SNA), SNB, and A point-nasion-B point (ANB) approximately 13years after surgery, with no statistically significant difference between SNA, SNB, and ANB curves (χ2=0.12) independent of the independent variables at SNB (χ2=1.9), SNA (χ2=1.3), or ANB (χ2=1.3). The average hazard ratio ranged from 0.89 to 1.02. Within the limitations of this study, MMA in the treatment of severe OSA is a highly skeletally stable long-term procedure independent of gender, age at the time of surgery, time to follow-up, and amount of surgical movement.