The local inflammatory response of the periodontium is a possible mechanism for systemic inflammation and the spread of infection. Both rheumatoid arthritis and periodontal disease are chronic inflammatory diseases. Rheumatoid arthritis is an autoimmune disease, and periodontitis has an infectious etiology with a complex inflammatory response; their clinical features involve the destruction of connective tissue and bone tissue. Genetic factors control the host response to the two diseases; host susceptibility and behavioral risk factors such as smoking play an important role in the development of periodontal disease and rheumatoid arthritis. In this paper, certain aspects of their correlation, including their characteristics in epidemiology, bacterial infection, and inflammatory cytokines and genes, are reviewed.