Objective. The two-year study of the efficacy of Ifnb-1B (infibeta) in patients with relapsing-remitting (RRS) and secondary progressive multiple sclerosis (SPMS) in the Moscow region with the criteria NEDA-3. Material and methods. Three hundred patients, 81 men and 219 women, aged from 18 to 67 years, including 227 with RRS and 73 with SPMS, were studied. The duration of disease was from 0.5 to 39 years, the level of neurological deficit on EDSS scale was from 1 to 6.5 points. All patients received infibeta. Results and conclusion. During the treatment with infibeta, the chance of exacerbation decreased by an average of 39.4 times (OR 39.4 95% CI; 16.6—122.7) during the first year, by 35.3 times (OR 35.3; 95% CI 13.5—131,2) during the second year. A statistically significant decrease in the probability of exacerbation is also confirmed in the conditional logistic regression model (p<0.001). MRI revealed the signs of exacerbation and progression of the disease only in 11.5% of patients; 54.9% of the patients met the criteria NEDA-3. The highest efficacy of infibeta is noted in patients with RRS, more than 3/4 of them responded to therapy with the absence of both clinical and MRI signs of exacerbation and increase in neurodegeneration. Thus, a good clinical result is achieved in patients with RRS and SPMS treated with infibeta. When using the NEDA-3 criteria, a positive result is achieved in more than half of patients.