A 31-year-old male with the complaint of severe limitation of mouth opening was referred to our department of Chonbuk National University Hospital. The physical status of the patient was hyposthenic. Extraoral examination showed no condylar movement of the both temporomandibular joints, no pain, no facial swelling or paresthesia. Intraoral examination showed several cervical caries on the upper anterior teeth, and gingival swelling on the whole dentition. Transcranial view showed no condylar movement, and narrowing of joint spaces. Chest P-A view showed straightening of thoracic, lumbar spine, and squaring of vertebrae of the same spines. Conventional lateral radiograph of cervical spine showed calcification of the intervertebral ligament. Computed tomograph showed extensive bone formation between temporal bone and the condylar head at both sides. Laboratory findings showed positive reaction on HLA-B27 histocompatibility antigen and increased level of IgA, IgG, ESR. Based on the clinical, radiographic, and the laboratary findings, final diagnosis was made as bony ankylosis of the both temporomandibular joints secondary to ankylosing spondylitis.