Rheumatoid arthritis (RA) is a chronic inflammatory disease of the joints. The inflammatory process causes a significant disability and may involve internal organs. The efficacy of disease modifying anti rheumatic drugs is widely accepted. However, the outcome of the treatment with these agents is known to vary among patients. Recently, the pharmacogenomic studies on methotrexate, sulfasalazine and tumor necrosis factor-alpha inhibitors have been reported, suggesting that the pharmacogenomic approach may be useful for the treatment of RA. Although there are points to be considered before the translation of the pharmacogenomic date into clinical practice, pharmacogenomics is considered to be an important tool for development of individualized medicine in the treatment of RA.