: Chronic destructive periodontitis is no longer considered to be just a local inflammatory process afflicting the periodontal tissues, but a systemic infection. Bacteria, their products and various pro-inflammatory cells and substances can penetrate into the blood stream and infect distant organs and structures. Periodontitis and rheumatoid arthritis indicate several common histo-pathological correlations, as the destroyed osseous tissues and cartilages are permanently washed with inflammatory fluid full of proteolytic and osteolytic substances. Although exact causal and molecular associations between both diseases have not been explained yet, there are some common etiopathogenic correlations that can have influence on relationship between both diseases. Among these factors belong: a positive finding of common genes, genetic polymorphisms and hyper-inflammatory types of some immune competent cells and molecules, common cytokine profiles and increased concentrations of pro-inflammatory mediators in periodontal and joint structures. Periodontitis and some periodontal pathogens can influence various auto-immune reactions connected with rheumatoid arthritis (RF, anti-CCP). Possible causal associations are indicated in some studies dealing with treatment of RA, when a beneficiary effect of RA treatment led to improvement of some periodontal parameters. This relationship works both ways; the periodontal therapy had positive influence on some markers of rheumatoid arthritis. This provides sufficient theoretic evidence to perform professional and personal oral hygiene in a more active way.