A case of severe ankylosing spondylitis involving the entire spine was to be operated for lumbar osteotomy. She had fixed rigidity of the cervical spine with minimal rotational movement, inability to lie down supine and severe restrictive lung disease with hypoxemia (pO2 = 65 mmHg). An awake intubation was performed and the patient was operated under general anaesthesia in the prone position. Intraoperative "wake-up" test was performed to judge whether extent of straightening was excessive. Postoperatively, she was electively ventilated and extubated uneventfully after 24 hours.