Background and Aim: The main purpose of periodontal treatment is to alleviate the clinical symptoms of inflammation. Photodynamic therapy which consists of light source and photosensitizer is believed to be influential as an adjunct to the conventional treatment in periodontitis. The aim of this study was to clinically compare the effect of using a single episode of photodynamic therapy as an adjunct treatment to scaling versus scaling per se within a three-month period in patients with chronic periodontitis in Isfahan.Materials and Methods: This interventional clinical trial was performed on 20 patients with mild to moderate chronic periodontitis, with pocket depth of 3-6mm and bleeding on probing in at least 3 teeth. Based on split-mouth design, each patient received scaling in one quadrant (as control group) and scaling accompanied by photodynamic therapy in the other one (as the case group). Clinical parameters including pocket depth, clinical attachment loss, bleeding on probing andpapillary bleeding index were measured initially and 90 days after treatment. The results were analyzed using Independent T-Test, Paired T-Test, Mann-Whitney and Wilcoxon Tests.Results: Bleeding indices decreased significantly, with a significant difference between two groups. (p<0.001) Although, the difference of reduction in pocket depth and clinical attachment loss was not significant between two groups (p=0.61 and p=0.14 respectively), decrease in these parameters after treatment was significant in each group (P<0.001).Conclusion: Using a single episode of photodynamic therapy was beneficial for reducing bleeding indices but it did not have extra clinical effects when compared with scaling per se.