Background: Melatonin is a free radical scavenger and has antioxidant and anti-inflammatory properties It is also has osteoinductive properties  on bone. GCF osteocalcin levels are more revealing than serum or saliva levels regarding bone turnover in periodontium. Aim: The aim of this study was to assess the effectiveness  of  local drug delivery of  Melatonin gel as  an  adjunct  to  scaling  and  root  planning  in  the  treatment  of  moderate chronic periodontitis. Patients and methods: Split mouth design was utilized upon fifteen chronic periodontits patients. Clinical parameters (Gingival Index, Plaque Index, Clinical Attachment Level, probing Pocket Depth) were recorded at baseline and after twelve weeks after treatment. GCF samples were collected at baseline and twelve weeks after treatment. All patients were received scaling and root planning, the test sites only were locally injected with Melatonin gel. Results: The clinical parameters (PI, GI, PD, CAL) showed highly significant improvement in the test sites (SRP+Melatonin) Also the test sites showed statistically high significant reduction in GCF OC than in control sites p < 0.001. Conclusion: The local application of melatonin gel offers a promising therapeutic approach in periodontal treatment.