The prevalence of polymorphism -1486T/C of the TLR-9 gene was studied in 44 patients with chronic Epstein-Barr virus infection (CEBV). The control group for the study of the polymorphisms prevalence of -1486T/C of the TLR-9 gene was 40 healthy donors. Three main genotypes of -1486T/C of the TLR-9 gene were identified based on the obtained results – TT, TC, CC. Investigation of the occurrence frequency of individual genotypes revealed the dominance of the TC genotype, compared with the homozygous TT and CC genotypes. The study of -1486T/C of the TLR-9 gene polymorphism frequency distribution for different genotypes demonstrated the specificity of changes in the TC genotype in patients with CEBV and the absence of such for the TT and CC genotypes. These results confirm the important role of the TLR-mediated signaling in the pathogenesis of the disease, which is necessary to determine the genetic background associated with the course of the disease and its possible consequences. These are the aspects that will further enable the identification of risk groups among such patients and provide timely therapy. The analysis of the results of the -1486T/C polymorphism of the TLR-9 gene revealed three main genotypes –TT, TC, CC. Investigation of the occurrence frequency of individual genotypes revealed the dominance of the genotype TC, compared with the homozygous genotypes of TT and CC. The study of frequency distribution of the polymorphism -1486T/C of TLR-9 for different genotypes demonstrated the specificity of changes in the TC genotype and the absence of suchin the TT and CC genotypes in patients with CEBV.Our study for the purpose of determining the 1486T/C polymorphism of the TLR-9, that is associated with chronic forms of CEBV infection, confirms the important role of TLR-mediated signaling in the pathogenesis of this disease, which is necessary to determine the genetic background associated with the course of the disease and possible consequences of CEBV. These aspects will further enable the identification of risk groups among such patients and provide timely therapy.Analysis of the results allowed establishing the following:1. The 1486T/C polymorphism of the TLR-9 gene is significantly more frequent in patients with CEBV than in the control.2. The frequency distribution of the -1486T/C polymorphism ofthe TLR-9 gene allowed the establishment of the association of the genotype TC with chronic forms of the EBV infection, which is very specific for this group of patients.