Interleukin (IL) - 18 may be one of the cytokines responsible for initiation and progression of periodontal destruction. IL-18 concentration in gingival crevicular fluid (GCF) and serum increases proportionally with the progression of periodontal disease. Periodontal inflammation may not successfully resolve because of accumulation of IL-18.Periodontal inflammation may not successfully resolve because of accumulation of IL-18. Further, the treatment aimed at arresting periodontal disease progression resulted in statistically significant reduction in the levels of IL-18 both in GCF and serum proportionally. It is very probable that the relatively high levels of IL-18 in GCF in periodontal disease signify it as an important factor in periodontal destruction. Thus, it can be considered as an inflammatory biomarker for periodontal disease and deserves further considerations in the development of preventive and therapeutic methods for treating periodontal disease.