BDNF, IL-6 and oxidative stress markers have a distinct role on the process of demyelination in multiple sclerosis. Distinct mechanisms of influence on inflammatory and neurodegenerative phase are not clarified. 60 subjects meeting the criteria for RRMS (19 men and 41 women) and 66 healthy control subjects (24 men, 42 women) were included in the study. The average age of patients and healthy people is around 43,5 years. The levels of the neurotrophin BDNF (proBDNF and mBDNF) and IL-6 were determined from the blood of the subjects by an ELISA test and oxidative stress markers (MDA, GSH, catalase and carbonylated proteins) were determined from subjects by the spectrophotometric method and correlated with the number of demyelinating T2/FLAIR lesions and gadolininium enhanced lesions. The correlation of the ratio of the mentioned physiological parameters with the degree of disability (EDSS), cognitive (MoCA test) and depressive deficit (BDI-II questionnaire) was determined. A statistically significant (P<0.001) negative correlation of serum markers of oxidative stress levels of glutathione (GSH) on the development of cognitive changes in subjects with RRMS tested with the MoCA test was shown. This is the first study of subjects with RRMS that performed the mentioned research of serum glutathione levels on the degree of congitive damage tested by the MoCA test. The development of cognitive changes in this study, verified by the MoCA test, was statistically significantly influenced by the positive number of MR lesions (T1, T2, FLAIR), degree of depression, EDSS, age, and GSH values. Subjects with higher MoCA test values were younger, had a lower degree of neurological disability, were less depressed and had lower glutathione values and fewer demyelinating lesions on MRI. Glutathione could be a potential marker of cognitive deficit progression in patients with RRMS.