The aims of our study were to determine the correlation of the TYMS 28bp VNTR (rs34743033), MTHFR [677C>T (rs1801133) and 1298A>C (rs1801131)], ATIC 347C>G (rs2372536), MTR A2756G (rs1805087) and MTRR 66A>G (rs1801394) polymorphisms with the clinical response and adverse drug reactions (ADRs) to MTX treatment in Chinese RA patients. The gene discussed is MTHFR; the disease is rheumatoid arthritis.