Limited knowledge on the role of transforming growth factor beta 1 (TGF-_1) in various periodontal disease types and particularly in advanced periodontitis warranted the present study in which we followed the dynamic immunohistochemical (IHC) expression of TGF-_1 in periodontal inflammation in order to reveal the biological role of TGF-_1 in various periodontal diseases ,so it was planned to conduct this study and examine TGF-_1 IHC expression in healthy & diseases gingival tissue sections & test whether TGF-_1 IHC expression is correlated with the clinical periodontal parameters, intensity of microscopic inflammation and the severity of the periodontal diseases.