Mandibular prognathism was defined by John Hunter as follows : The lower jaw projecting too far forwards so that the foreteeth pass before those of upper jaw, therefore disfigurement and malocclusion are the two of facial main characteristics.
 Mandibular ramus osteotomy by vertical osteotomy or sagittal splitting osteotomy recently has come into more common use. Although preoperative and postoperative orthodontic management is indispensable in surgery of this type, we occasionally encounter patients who are intolerant to a long duration of orthodontic treatment and intermaxillary fixation. We describe surgical refinement accomplishing mandibular anterior segmental osteotomy, recession genioplasty by horizontal osteotomies and decortication of the anterior portion of the bony bar for a minor degree of mandibular prognathism. In results, the amount of setback is limited to 4 to 5mm, no intermaxillary fixation is required and no orthodontic treatment, in this operation, is needed. This procedure can obtain a rapid aesthetic improvement. We used this procedure in 8 patients (3 males and 5 females) with a mild mandibular prognathism. No major complications occurred throughout the follow-up period except transient paresthesia of the mental nerves, otherwise all patients were satisfied with the result.