Periodontitis is a chronic condition affecting the supporting tissues of teeth leading to an imbalance of the antioxidant-oxidant system. Melatonin being an immune modulator and antioxidant also controls circadian rhythms and is a hormone. Aim: The present study aimed to assess the impact of non-surgical periodontal therapy on the levels of melatonin in the saliva of subjects having periodontal diseases Methods: 90 subjects were divided into 3 groups of equal participants (n=30) having periodontitis (Group I), gingivitis (Group II), and healthy periodontium (Group III). Saliva samples (unstimulated) were collected at baseline and 30 days following scaling and root planing in Group I and II. The data were analyzed statistically using the t-test and significance with p<0.05 for results formulation. Results: The study results showed that the levels of serum melatonin were lower in subjects having chronic periodontitis (Group I) compared to the other two groups. The difference was statistically significant with p<0.05. A marked improvement was seen in the levels of serum melatonin in subjects having gingivitis and chronic periodontitis. Conclusion: A significant negative correlation is seen between the severity of periodontal disease and the levels of serum melatonin. A significant increase in the levels of serum melatonin is seen after scaling and root planing depicting the protective role of melatonin in periodontal disease making it an effective biomarker in periodontitis.