The aim of the study to evaluate the effect catechin gel on glutathione levels in GCF following nonsurgical periodontal therapy (NST) in chronic periodontitis patient. Thirty patients with chronic periodontitis (113 sites) were randomly divided into two groups, one was treated with scaling and root planing(SRP) + placebo(Group A) and other with SRP+Catechin gel(Group B).All clinical parameter were assessed prior to treatment (baseline), 1month and 3months. Result: Twenty patients completed the study, group B showed significant improvements over group A. Conclusion: Catechin gel with nonsurgical periodontal therapy improved GSH levels and clinical parameters as compared to nonsurgical therapy alone.