Abstract Aim: Oxidative stress represents a cornerstone of a wide range of chronic diseases. Studies have identified an inconsistent effect of green tea on regulating oxidative stress. We aimed to examine the evidence from randomized clinical trials (RCTs) to assess the effects of green tea on oxidative stress markers including malondialdehyde (MDA), and total antioxidant capacity (TAC) in adults. Methods: A systematic search of English language publications in PubMed, Scopus and Embase was performed up to September 1, 2020. Data were pooled using the random-effects method and were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI). Results: Fourteen RCTs met inclusion criteria. There was a significant relationship between green tea and TAC. Our results indicated that green tea had significant effects on TAC (weighted mean difference [WMD]: 0.18; 95 % CI, 0.07, 0.29, P =0.001) and significant heterogeneity between studies (I2 = 98.6%, p <0.001) which was largely related to sex and BMI. Subgroup analysis in TAC identified a significant relationship except in low dose and obese individuals. No relationship between MDA and green tea was observed overall and in all subgroups. Conclusions: We found that the intervention with green tea significantly increased the TAC, while, it had no significant effect on MDA. Key Words: green tea, oxidative stress, total antioxidant capacity, malondialdehyde.