Camellia sinensisis traditionally used in many polyherbal preparations for the treatment of different diseases and infections. Its action has been associated with its antioxidant activities. In this study, antioxidant effect of Camellia sinensis on hydrogen peroxide-induced human lymphocyte cell cultures was estimated. Camellia sinensis showed high contents of ascorbic acid, phenols, flavonoids, and flavonols. Good scavenging activity was evident by scavenging assays e.g. 2,2-DiPhenyl-2-Picrylhydrazyl Hydrate (DPPH), 2,2-Azinobis (3-ethyl-BenzoThiazoline-6-Sulfonic acid (ABTS) radical assay and reducing power assay. Moreover, High Performance Liquid Chromatography (HPLC-UV) chromatographs showed many notable peaks of unidentified bioactive compounds. In vitro antioxidant actions were determined by the activities of catalase (ELISA kit method), superoxide dismutase, lipid peroxidation and total protein contents on lymphocyte cell cultures. In vitro experimental trial showed strong antioxidant repair mechanism of plant against oxidative stress. Results of extraction with solvent methanol showed the highest antioxidant activity. Camellia sinensis is promising source of natural antioxidants and further studies might be a likely source of its use in remedy of different diseases.