Periodontal disease and rheumatoid arthritis are both inflammatory diseases. It is well known that there are associations between periodontitis and other systematic diseases like cardiovascular disease, diabetes mellitus and alterations during pregnancy. This review analyses the literature available dealing with the relationship between periodontal disease and rheumatoid arthritis. Periodontitis is an infection disease which causes inflammation. Porphyromonas gingivalis is the most common pathogen connected with periodontitis. This bacterium has the peculiarity of being able to produce peptidylarginine deiminase, a proteolytic enzyme with an important role in inflammatory diseases like rheumatoid arthritis. Furthermore, several case-control studies related the clinical activity and biochemical markers levels of rheumatoid arthritis with non-surgical periodontal treatment. The studies confirm that the non-surgical treatment of periodontitis improves both the biomarkers and the clinical situation of rheumatoid arthritis. In addition to this, the fact that antibiotics, such as minocycline, have been successfully used for the treatment of rheumatoid arthritis for many years could explain the relationship of rheumatoid arthritis with infection diseases like periodontal disease. The relationship between rheumatoid arthritis and periodontal disease seems clear, but it is necessary to carry out more studies with a greater number of casecontrols and a longer period of follow-up research.