Masseter muscle hypertrophy (MMH) is most probably a congenital, genetically determined anomaly. Thus we should refer to it as hyperplasia rather than hypertrophy of the masseteric muscle. Excision of the internal layer of the masseter muscle and reduction of the thickened bone in the region of the mandibular angle, via an intraoral approach, is the treatment of choice. Immediately after surgery it is necessary to apply a fixed compression bandage to the masseteric region in order to obliterate dead space which would otherwise be filled by a haematoma which in turn leads to prolonged postoperative trismus. After removal of the bandage it is necessary to institute mouth opening exercises. Very good esthetic and functional results were achieved.