Twenty-four patients who had undergone osteotomies for maxillary impaction and mandibular advancement were evaluated for stability using cephalometric analysis. The follow-up time interval was 9 +- 3 months after surgery. Fixation consisted of miniplates in the maxilla and bone screws in the mandible. Intermaxillary fixation was limited to two days. Although individual responses varied, the results indicated an optimum level of skeletal stability. Patients that had a concurrent advancement genioplasty (n = 9) showed a similar level of stability. Significant correlations between surgical movements and postoperative changes did not exist. The preoperative mandibular plane angle and the magnitude of mandibular advancement were not reliable predictors of relapse. The results were compared to another study of isolated mandibular advancement with rigid fixation. The postoperative horizontal change at Pg was not significantly different between patients with bimaxillary surgery or isolated mandibular advancement