The purpose of the present study was to evaluate the efficacy of the Photodynamic therapy in addition to the classical treatment with scaling root planing compare to subgingival chlorhexidine irrigation. A 20 patient of chronic generalized periodontitis with probing depth more than 5mm, were included in the study. According to split mouth design, for one quadrant scaling and root planning with Photodynamic therapy was performed and other side scaling and root planning with chlorhexidine irrigation was done as a control group. A statistically significant difference in median Gingival Index score over a period of 20 days from baseline was observed  in  the site of the test group as compared to control site. The present study supports the treatment approach of Photodynamic therapy an adjunct to routine scaling and root planning. Photodynamic therapy is as efficient and safe to be used in addition to root planing when compared to sub gingival irrigation with scaling and root planning.