The purpose of this review is to evaluate the association between rheumatoid arthritis (RA) and periodontopathic bacteria. Clinical studies of RA and periodontal disease have provided evidence for a significant association between the two disorders. Patients with long-standing active RA have a substantially increased frequency of periodontal disease compared with that among healthy subjects. High levels of oral anaerobic bacterial antibodies have been found in the serum and synovial fluid of RA patients. Porphyromonas gingivalis, Tannerella forsythensis, and Prevotella intermedia have been identified in RA synovial fluid. Ornidazole, levofloxacin, and clarithromycin are used in the treatment of infections caused by anaerobic bacteria. These antibiotics have been shown to be effective against RA. The evidence in this review indicates that oral bacteria directly associate with etiopathogenesis of RA.