The development of an immune-inflammatory response during periodontitis in the susceptible individual results in local production of a variety of inflammatory mediators including IL-1, IL-6 and tumor necrosis factor- (TNF- ), synthesis, and release of prostaglandins and other arachidonic acid metabolites within periodontal tissues. In addition the host cells stimulated the matrix metalloproteinases by a variety of infiltrating and resident cells. Host cells further release mediators including reactive oxygen species such as nitric oxide which has been shown to be toxic when present at high levels. Therefore though chronic bacterial exposure is a prerequisite for gingival inflammation and periodontal tissue destruction 80 % of the periodontal tissue destruction is host mediated, involving local production of a variety of inflammatory mediators due to the development of an immune-inflammatory response during periodontitis in susceptible individuals. Therefore,this book gives a brief destruction about the host mediated pathogenic mechanisms in periodontal disease.