Background: Periodontal diseases are multifactorial, inflammatory diseases that, when left without treatment may results in the destruction of tooth-supporting structures and finally may cause tooth loss. Diode laser therapy as an adjunct to non-surgical periodontal treatment of periodontal pockets has been increasingly encouraged by some researches but experimental proves have not yet supported the use of laser therapy. Aim: The objective of this single controlled clinical study was to assess the effect of a 940-nm diode laser as an adjunct to scaling and root planing (SRP) therapy in the treatment of periodontal pockets. Methods: Fifteen patients in need of periodontal treatment with periodontal pocket ≥ 4 were selected for this split-mouth clinical study. Quadrants were enrolled into either control group treated by conventional scaling and root planning or test group treated by diode laser 940nm as an adjunct with SRP in contralateral quadrants. Baseline data, including plaque index (PI), gingival index (GI), probing pocket depth (PPD) were recorded before the treatment and 3 months post treatment. Results: plaque index (PI), gingival index (GI), probing depth (PD) were significantly reduced after 3 months in both groups. No significant differences were found in reduction mean of PI, GI, PPD. Conclusion:The use of the diode laser as an adjunct to scaling and root planing did not offer any superior clinical benefits over conventional scaling and root planning.