STUDY DESIGN Case report of spontaneous Fielding and Hawkins Type I atlantoaxial rotatory fixation in a 78-year-old man after hemiplegia and homonymous hemianopsia caused by cerebral infarction. OBJECTIVES To describe a case of spontaneous atlantoaxial rotatory fixation in old age and review previous adult cases of atlantoaxial rotatory fixation without fracture. SUMMARY OF BACKGROUND DATA Atlantoaxial rotatory fixation in adults is a relatively rare finding and is mainly caused by trauma. To the author's knowledge, there has been no previous report of spontaneous atlantoaxial rotatory fixation in old age. METHODS The patient's head was fixed in a 40 degrees left-rotated position. Left hemiplegia and homonymous left-side hemianopsia developed due to cerebral infarction. Computed tomography of the cervical spine clearly showed rotatory fixation of the atlas on the axis. RESULTS Successful reduction was obtained after 1 day of skull traction. CONCLUSIONS It was hypothesized that repeated left-rotational stress due to homonymous hemianopsia loaded to the atlantoaxial joint caused abnormal laxity of the joint.