An investigation into the involvement of the temporomandibular joint in rheumatoid arthritis is described. There is evidence to show that is is affected in two-thirds of all cases of the disease, and this figure agrees broadly with other recent studies. The clinical and radiographic presentation is discussed and its relationship to degenerative disease (osteoarthosis) of the temporomandibular joint is shown. The clinical course of this manifestation of rheumatoid arthritis is proposed and a line of treatment is suggested.