The present study aimed to investigate the association of the ATP-binding cassette subfamily B member 1 (ABCB1) 3435C/T and methylenetetrahydrofolate reductase (MTHFR) 677C/T and 1298A/C polymorphisms with susceptibility to RA and RA subtype. This evidence concerns the gene ABCB1 and rheumatoid arthritis.