Ramzi Ibrahim sarab¹, Laila Ibrahim Ragab Sidky² , Mohamed Mahmoud Anees³  and Ziyad Mohamed Essam Ei-Din Tawhed^{4 1}BDS, Faculty of Dentistry, al-zawaia University, Libya. ²Professor of Oral Medicine, Periodontology, X-Ray & Diagnosis, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. ³Assistant Professor of , of Oral Medicine and Periodontology, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. ⁴Assistant of Clinical Pathology, Faculty of Medicine, Mansoura University, Mansoura, Egypt. Abstract: Objectives: The aim to evaluate salivary and serum levels of platelets activating factor in chronic periodontitis patient with and without diabetes. Methods: A total of forth patients with moderate to severe chronic periodontitis were selectively collected for contribution in the present study. Results: showed significant differences in platelet activating factor in saliva and serum between different groups. Group IV (type II diabetes mellitus) showed the highest level of platelet activating factor in saliva and serum followed by group III (type I diabetes mellitus) then group II (chronic periodontitis).  Group I (control) showed the lowest level of platelet activating factor in saliva and serum. A positive correlation was observed between PAF levels and periodontal parameters. PAF levels in both serum and saliva in patients had significantly positive correlation with periodontal parameters. Conclusions: PAF may be used for evaluation of the severity of chronic periodontitis in healthy and diabetic patients. It may also be responsible for the development and increased incidence of complications which are commonly found in diabetes. Keywords: Salivary. platelet activating factor, serum platelet activating factor, Diabetic, non-Diabetic, chronic Periodontitis.