Introduction. Neurodegeneration (ND) is the basis of the gradual increase in neurological deficit and cognitive impairment in patients with multiple sclerosis (MS). Morphometry of the brain is the method for monitoring of ND. The possibility of using neuropsychological tests for this purpose is being actively discussed. Objective. To examine the effect of treatment with interferon beta-1b (IFNb-1b) on the development of the neurodegenerative process according to morphometry and cognitive testing. Material and methods. Twenty-three patients with relapsing-remitting MS were examined. The control group included 10 healthy people. All patients received IFNb-1b in a dose of 9.6 million IU. EDSS, MSFC, depression and anxiety Beck test, Wechsler test, magnetic resonance imaging (MRI) of the brain, voxel morphometry with FreeSurfer 5.3 were used. The EDSS score was 4.0 before treatment. Results. In MS patients, MSFC and Wechsler scores were worse in comparison with similar indicators of the control group. Deterioration of neurological status, motor function test and PASAT during exacerbation was identified in 7 patients. Morphometry revealed the increase in hypointense white matter lesions (HWML) (p<0.05) in patients with MS. There was a downward trend in the cortical and subcortical gray matter volume and the increase in ventricular volume. A direct correlation between the amount of HWML and the degree of disability on EDSS scale (p=0.018), the inverse correlation between HWML and Wechsler test, PASAT (p<0.05) were identified. After a year of therapy, there were no statistically significant changes in motor and cognitive functions and no signs of «pseudoatrophy». Conclusion. Morphometric data in MS were changed compared to healthy controls. There were correlations between morphometry results, disability and cognitive dysfunction. After a year of IFNb-1b therapy, there were no significant changes in cognitive function and EDSS.