Abstract: Sulfur mustard (SM) is a chemical warfare agent that increases oxidative stress in veterans. The literature assessing oxidant/antioxidant parameters in SM-exposed veterans contains conflicting results. A total of 11 relevant studies were identified and screened. Data were extracted, and effect size and heterogeneity were assessed. The analysis revealed significant elevations in levels of malondialdehyde (MDA, an indicator of lipid peroxidation), catalase (CAT), and a reduction in glutathione (GSH) following SM exposure while superoxide dismutase (SOD) and total antioxidant levels did not change. The meta-analysis revealed that the MDA and CAT levels significantly increased in the two post-exposure sampling times (15-20 and 21-33 years) except for theGSH level, which decreased only in the post-exposure sampling time of 21-33 years. The subgroup meta-analysis of the type of analyzed samples indicated that SOD and CAT levels were only increased in the serum/plasma samples, while GSH was decreased. BALF/sputum and erythrocyte samples also revealed significant increases in MDA and SOD levels while GSH level was significantly decreased. This meta-analysis concluded that SM exposure affects the balance between oxidants and antioxidants, promoting oxidative stress that may persist long after exposure. This condition highlights the need for strategies to enhance antioxidant defenses in SM-exposed veterans.