In sagittal ramus split osteotomy of the mandible, rigid internal fixation of the fragments with screws has become one of the main fixation techniques. This screw-fixation has the advantages to reduce the period of intermaxillary fixation which is unpleasant for patients. On the other hand, it is necessary that the condyles are exactly positioned to the glenoid fossa after surgical correction. Incorrect repositioning of the mandibular ramus will induce serious problems, e.g. relapse caused by mandibular movement, pain of temporomandibular joint, occlusal dysfunction, etc. Some surgeons make efforts to avoid the problems by various methods. Postoperative radiographs are one of the procedures, which taken while the patient is on the operating table. Various appliances are also used for the purpose of repositioning ramus at operation. We have devised a simple appliance that allows the surgeon to be sure that the position of the external fragments of the mandibular ramus will be precisely established. We named this appliance "ramus repositioner". It consists of 1.2 mm orthodontic wire in diameter, cold-cure acrylic resin and titanium mini-plates. It is fabricated and tried to fit prior to the operation. At operation, both ends of its orthodontic wire are inserted into the tubes on the buccal surfaces of the maxillary first molars. The positions of the mandibular ramus involved condyles are recorded by mini-plates on this appliance with its exclusive self-tapping screws preoperatively. Then the appliance is removed and mandible is splitted. After splitting, the appliance is replaced with the screw hole landmarks that tapped before.(ABSTRACT TRUNCATED AT 250 WORDS)