As a result of the study, the relationship of the alleles/genotypes of the IL1B rs16944, IL10 rs1800872, CTLA4 rs3087243, NFKB1 rs28362491 polymorphic loci and the TNFA rs1800629*A - LTA rs909253*G haplotype with the methotrexate efficacy in JIA has been established (taking into account the differences by sex). This evidence concerns the gene CTLA4 and juvenile idiopathic arthritis.