Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system with different disorders of neurological and higher cortical functions. It is important to identify biomarkers that can control the dynamics of neuropsychological changes and predict the progression of this process. The aim of the study was to investigate the pathogenic and clinical significance of serum autoantibodies to the myelin basic protein (MBP) and histone h1 in the occurrence of neurological and neuropsychological disorders in patients with MS. Fifty-five patients diagnosed for MS were examined. A general clinical and neurological examination, determination of cognitive status, depression level and the content of autoantibodies to histone h1 and MBP in the blood serum were conducted. Blood serum samples of 20 healthy volunteers were used as control. The serum of patients with MS was shown to contain antibodies of IgG class to MBP and histone h1. The level of anti-histone h1 IgG-antibodies in blood serum of MS patients was found to be higher compared with the level of anti-MBP IgG-antibodies (P < 0.05). Increased levels of anti-MBP antibodies correlated with the severity of trunk ataxia, impaired conceptualization, and mood. High level of anti-histone H1 antibodies correlated with the severity of paresis, trunk ataxia, impaired conceptualization, semantic language, and mood. The level of anti-histone H1 antibodies in blood serum of MS patients might serve as a biomarker of inflammatory and, probably, of the neurodegenerative processes of this disease and determine the dynamics of clinical course of the MS. anti-MBP antibodies play an important role in the pathogenesis of the MS and are an additional marker of the severity of the clinical course of neurological and some neuropsychological disorders. K e y w o r d s: multiple sclerosis, IgG-autoantibodies, histone h1, myelin basic protein, cognitive impairments, depression.