Objectives: Photodynamic therapy applies to the elimination of target cells by reactive oxygen species using a photosensitizing agent and a sufcient wavelength of light. It is a new, non-invasive approach to preventing infection. It is now an upcoming alternative treatment modality for periodontitis patients as a supplement to traditional scaling and root planing. The objective of the present study was to assess and compare the effect of photodynamic therapy with conventional Scaling and Root planing in patients with chronic periodontitis. Methods: The study included a minimum of 5 non-smoking males with mild to moderate periodontitis. Clinical parameters such as plaque index, gingival index, gingival bleeding index, pocket probing depth, clinical attachment level; microbiological parameter – anaerobic bacterial CFU count in subgingival plaque samples and biochemical parameter – GCF SOD levels were evaluated at baseline and 28 days postoperatively. The obtained data were analyzed using SPSS (SYSTAT 12) statistical software. The Wilcoxon signed Rank test was used to compare the mean values of various parameters before and after treatment. Results: The results of the study show that all clinical parameters improved from baseline to day 28. Following therapy, the mean levels of the anaerobic bacterial CFU and GCF SOD have decreased dramatically. Conclusion: The results of this study suggest a signicant improvement in clinical, microbiological and Biochemical parameters with the use of PDT as an adjunct to conventional SRP in chronic periodontitis patients