The management of mandibular prognathism and retrognathism was revoluted by the advent of the technique of bilateral sagittal split ramus osteotomy(BSSRO) as described by Obwegeser and Trauner in 1957. The BSSRO of the mandible has been used for nearly 50 years and has undergone numerous modifications and improvements. Most patients, treated by this surgical operation, express their satisfaction with improved facial esthetics, masticatory function and others. But several complications associated with BSSRO may appear. Especially among them, facial nerve palsy following BSSRO is rare but serious problem. We treated for facial nerve palsy following BSSRO by physical therapy, steroid therapy and surgical intervention and then the result was favorable. Therefore we would like to report a case about a patient with facial nerve palsy after BSSRO with a review of the literatures.