A young girl 20 years old with mandibular prognatism has been treated with orthodontics and surgical treatment in between. Mandibular set back was done intra orally 5mm length with bilateral sagital split ramus osteotomy method. And rigid fixation was done by inserting three 2mm bicortical screws for stabilizing the fragment. This method allowed the bony segments to heal properly and allowed the patients to function sooner.