Only single cases with rheumatoid arthritis of the thoracic spine with vertebral subluxation have been reported to date. In a review of 100 patients with severe rheumatoid arthritis who had undergone occipitocervical fusion, arthritis of the upper thoracic spine with subluxation was discovered on conventional radiographs in four patients. Two additional patients were found elsewhere. Magnetic resonance imaging (MRI) was performed in three of the patients, confirming the diagnosis of subluxation of the upper thoracic vertebrae. In addition, MRI revealed encroachment on the anterior subarachnoid space and compression of the spinal cord.