This is to report a case of surgical correction for extreme micrognathia combined with TMJ The 30 years old male patient had sufferred from masticatory inability due to locked jaw since child hood after febrile arthritic illness on Rt. temporomandibular joint area, and facial disfigurement for asymmetric bird-face had been induced d end distinguished by his growing. After precise examination &, analysis the patient was treated by a serial approaches of unilateral condylectomy, physical exercise and mandibular augumentation as follows; 1. Rt. mandibular condyle being united fibrously was resected oy preauricular approach, and fascial interpositioning was performed to prevent reunion of the bony segments. 2. Early and active exercise to open the jaw had been rendered for 4 months. 3. The bilateral step sliding osteotomy lengthened the mandibular body and the grafted iliac bones were maintained in the inferior space by interosseous wiring and intermaxillary fixation for 6 weeks. In reviewing this case following points were noted. l. If the ease is unitaterai ankylosis, arthroplastic implant after condylectomy my not be utilized to prevent shifting and open bite. 2. Resection of proximal con4ylar segment more than 10 mm in width was not fallowed by recurrence of ankylosis without postoperative bite block to create intersegmental apace. 3. Active exercise soon after the operation being lasted until the second surgery were of value to improve and maintain the jaw excursion movement. 4. Step sliding augumentation of the mandibular body as much as 10 mm in length required bone graft at inferior defect, however, didn`t show any neuropathy nor vascular collapse. 5. To obtain better cosmetic result, chin plasty may be considered as additional augumentation & contouring.