The stability of osteosynthesis with the use of semirigid mandibular fixation was evaluated in 15 patients who underwent bimaxillary procedures for correction of Class III malocclusion. All patients received rigid fixation (4 miniplates and screws) in the maxilla. Cephalometric evaluation was performed before the operation, immediately after the operation, and at least 18 months after the operation. At the 18-month follow-up, a mean mandibular relapse of 2.2 mm, associated with an additional advancement of the maxilla of 0.27 mm, was observed. The dental relationship was substantially correct. Stability of mandibular fragments in this sample of patients depended on the stability of the maxilla. In addition, neither clinical damage to the temporomandibular joint nor lesions to the neurovascular bundle were detected.