The occurrence of temporo-mandibular joint (TMJ) disease in ankylosing spondylitis is not widely recognized and its incidence is disputed. Seventy-nine patients attending two routine rheumatology clinics were therefore examined by dental surgeon and nine (11-5 per cent) were considered to have specific TMJ involvement. These patients were older than the remainder, and had more extensive spinal and peripheral joint disease. Symptoms were mild and the predominant clinical feature was restricted mouth opening, which could present considerable difficulties during emergency anaesthesia. Bilateral condylectomy was undertaken in one patient with some benefit.