Rheumatoid arthritis(RA) is characterized by the presence of a relative state of imbalance between pro- and anti-inflammatory cytokines such as Interleukin(IL)17 and IL4, respectively. IL4 is supposed to regulate production of IL17 from T-helper (Th)17 cells. However, this regulatory function might be affected by singlenucleotide polymorphism (SNP) of IL4 receptor (IL4R) gene, rs1805010. The current study aimed to assess serum IL17 level in Egyptian patients with RA according toIL4Rrs1805010 genotypes,and to detect possibleassociations betweenIL17/ IL4R genotypesand clinical status, disease activity as well as effect of treatment. Serum IL17 was assessed by ELISA, and qPCR was used to determine the genotypes of IL4R SNP rs1805010. Serum IL17 was significantly increased in patients’ samples as compared to controls. According to IL4R genotypes, patients with AG and GG genotypes showed significantly higher IL17 levels than control subjects with corresponding genotypes. Within RA group, significantly higher IL17 were found in GG carriers compared to those with AA genotype. The G allele was significantly associated with higherythrocyte sedimentation rate(ESR), increased disease activity score in 28 joints |