Abstract: In 1973, the authors reported the use of an autograft of costochondral segment in the treatment of temporomandibular ankylosis. All the patients have now been followed up for 9 to 20 years. There has been no evidence of recurrence of ankylosis, and the function of the temporo-mandibular joint has remained to be good. Since 1978, we have used a bone fragment including the coronoid process as the substitute for the costochondral segment to treat temporomandibular ankylosis. Four cases were treated in this way, and the same curative effects have been obtained. Surgical Procedure and Method 1. Routine preoperative preparation. Sub-auricular incision. 2. Osteotomy （1） The position of the coronoid process and mandibular sigmoid notch is explored first. （2） Take a bone fragment which includes the coronoid process （Fig.1）. （a） Make a longitutinal osteotomy of the ascending ramus along the direction from the mandibular notch to the mandibular foramen. （b） Make an oblique osteotomy along the level of the mandibular foramen, the inner end of which being above the foramen and the outer end below it. Thus the injury to the inferior dental nerve and blood vessels can be avoided. On the other hand, a bone fragment of sufficient length can be obtained to restore the lost portion of the ascending ramus. （c） When the coronoid process is dissected from the temple muscle, the tendon of the muscle attaching to the tip of the coronoid process is preserved as much as possible. 3. The bone fragment including the coronoid process is made to fit to its grafting bed by: （1） making the tip of the coronoid process rounded with the aid of bone scissors; （2） covering the end of the coronoid process with the remnants of tendon and fixing it with sutures; （3） trimming the inner side of the bone fragment to make it fit into its grafting bed on the outer side of the ascending ramus. 4. After the implantation of the bone graft and fixation of it in place （Fig.2）, the wound is closed. Postoperative care and active exercise of the mandible are carried out as routine.