Purpose: The current clinical study was conducted to evaluate clinical and biochemical effects of photodynamic therapy in treatment of periodontal disease. Material and methods: The current study was conducted on twenty-eight (28) sites in fourteen (14) patients. A spilt-mouth design was used, sites were randomly selected from each patient, and assigned into two groups:(control group A) fourteen (14) sites received scaling and root planning only, and (test group B): fourteen (14) sites received PDT (Curcumin as photosensitizer agent was irradiated by diode laser beam) and another group without any laser beam in oral cavity, 5 patients received SRP only. Clinical parameters included probing pocket depth (PPD), clinical attachment level (CAL), Plaque index (PI), and gingival index (GI) were used to make clinical evaluation. ELISA analysis of human P.gingivalis IGg was done. Results: Comparison between the groups at baseline, one week and one month was showed significant difference in human P.gingivalis IGg which decreased in test group more than in control group. Conclusion: This clinical study illustrated that SRP in combination with PDT can be effective especially when used as an adjunctive therapy to the mechanical conditioning of the periodontal pockets. Although using Curcumin as natural photosensitizer agent have great effect on enhancement of inflammation in patients with periodontal disease.