Since 1987, the authors have performed mentoplasty for congenital mandibular deformities in 46 patients with the assistance of X-ray pantomoscanning. Mandibular deformities include: 1) Bilateral hyperplasia of mandibular angles and massetter hypertrophy; 2) Retrognathia or micrognathia; 3) Asymmetric mandibular deformity. In this paper, following problems are discussed: 1) The advantages of an extraoral approach in mentoplasty; 2) The importance of the X-ray pantomoscanning; 3) The specific feature of asymmetric chin; 4) The improvement of the silicon implant used in mentoplasty; 5) Evaluation of the composite operative result.