Background: Multiple sclerosis (MS) is considered as immune mediated disorderwith different disease course., Recently, oxidative stress was reported to share in the pathogenesis of MS. Aim:to investigate the role of serum glutathione peroxidase enzyme in pathogenesis of Multiple Sclerosis especially the Relapsing Remitting type (RRMS)and to assess the relation between it and disease characteristics. Methods: 45 patients with RRMS(23 in relapse and 22 in remission) (18 males and 27females) and 45 age, sex and body mass index (BMI) matched healthy subjects were included in this study. clinical assessment, general and neurological examination were done. MS Severity was calculatedusing expanded disability status scale (EDSS). Magnetic resonance imaging (MRI)brain and spine with gadolinium enhancement and visual evoked potential were done for all MS patients. Serum glutathione peroxidase (GPX)enzyme and routine laboratory tests were assessed.Results:reduced levels of GP in patients than controls. no significant difference detected between remitting and relapsing MS groups. In addition, there was statistically significant negative correlation between serum GPx and disease duration, physical MSIS. Also, an adverse correlation between serum GPx and gadolinium enhancement was recorded. Conclusion: Our study demonstrates significant low level of GPX among patients than control, this indicate its role in the MS pathogenesis,that might be important for new therapeutic strategies based on antioxidant approach in MS patients.