Periodontal diseases are a group of infectious diseases caused by predominantly Gram-negative, anaerobic bacteria that colonize the subgingival area. Inflamed periodontal tissues produce significant amounts of pro-inflammatory cytokines which may have systemic effects on the host being at risk for cardiovascular diseases, diabetes mellitus, pulmonary infections, osteoporosis and adverse pregnancy outcomes. It is well known that cytokines are recognized as being vital in the immunopathology of an ever-increasing number of diseases, and the production of ‘appropriate’ cytokines is essential for the development of protective immunity. IL-11 is a multifunctional cytokine first isolated in 1990 from bone marrow-derived stromal cells; Interleukin 11 is produced by a variety of stromal cells including fibroblasts, epithelial cells, and osteoblasts. In vitro studies from demonstrated that epithelial cells, fibroblasts and airway smooth muscle cells, produce IL-11 in response to TGF-ß1, IL-1, TNF-a, prostaglandin E2 (PGE2), parathyroid hormone, 1,25- dihydroxyvitamin D3, histamine, eosinophil major basic protein, and specific respiratory The level of -IL-11 as it is an anti-inflammatory cytokine can be considered as an indicator for Periodontal infection, which is a reservoir for Gram-negative anaerobic microorganisms, lipopolysaccharides, and inflammatory mediators. It was proved that Interleukin-11 enhanced alkaline phosphatase activity, osteocalcin and bone sialoprotein gene expression in the presence of ascorbic acid. Interleukin-11 induced type 1 collagen and tissue inhibitor of metalloproteinase-1 production in periodontal ligament cells. Anti-Inflammatory cytokines has been reported to have an important role in inflammatory diseases like chronic periodontitis by many authors. Consequently, the aim of this study was to estimate the level of Interleukin-11 in Gingival crevicular fluid of patients with chronic periodontitis before and after treatment. The study was performed on a total 30 individuals that were divided into two groups ; 10 individuals with healthy periodontium as control group and 20 patients suffering from mild to moderate chronic periodontitis as periodontitis group which subdivided into 10 patients received systemic antibiotics and 10 patients recieved hexitol mouthwash. Both groups were periodontally evaluated by measuring the clinical parameters to determine Gingival index, Pocket depth, Clinical attachment loss, and also gingival crevicular fluid samples were collected before the periodontavli rthueserasp syu acnhd a(s6 -r8e)s wpieraetkosr ya ftseyrn pceyrtiioadl,o nptaarla tihneflruaepnyz. a and rhinovirus. The IL-11 assay was carried on using the RLISA technique for quantitative determination of IL-11. The results of ELISA, clinical parameters from the patient group before and after treatment were compared with those obtained from the control group.The results showed that the concentration level of IL-11 was significantly increased in chronic periodontitis group after treatment weather by systemic antibiotics or Hexitol mouthwash in comparison to its level before treatment. Before periodontal therapy the control group was have the higher levels of IL-11 GCF concentrations than those of chronic periodontitis group. From these results we could suggest a possible casual relation between periodontal disease and Interleukin-11. Consequently the periodontics shoud be directed towards the possibility of using IL-11 in treatment plans of periodontal diseases.