Objective. To verify a role of oxidative stress in the pathogenesis of multiple sclerosis (MS) and to develop oxidative stress prognostic criteria of disease course and treatment recommendations. Material and methods. We examined 220 patients with different clinical forms and phases of MS. The lipid and protein free-radical oxidation markers were measured using the following parameters: ketodienes, diene conjugates, malondialdehyde, and Schiff bases. The functioning of the endogenous antioxidant defense system was assessed using y the activity of vitamin E, general and non-protein SH-groups, which represented the nonenzymatic segment of the antioxidant defense system. The enzymatic segment markers were superoxide dismutase, glutathione peroxidase, and glutathione reductase. Results and сonclusion. The findings revealed significant differences in the oxidative stress intensity indices in patients with different clinical forms and phases of MS, which made it possible to predict disease progression and prescribe the complex antioxidant treatment in the evidence-based practice.