Aim: Purpose of the present research was to assess the effectiveness of Er,Cr:YSGG laser in comparison or as an adjunct to non-surgical treatment for periodontitis. Methodology: In a randomized, single-blinded, controlled trial, 27 patients were recruited. Using a split-mouth design, two quadrants were randomly allocated into either a test group or a control group. The test quadrants received Er,Cr:YSGG laser (ERL) (100 mJ/pulse;15 Hz to hard tissue and 50 mJ/pulse; 30 Hz to soft tissue) plus SRP treatment, while the control quadrants received SRP only. We evaluated periodontal indexes, including probing depth (PD), clinical attachment level (CAL), bleeding index (BI), and plaque index (PLI) at baseline, 3 months, and 6 months