We aimed to investigate GSTM1 CNV in Rheumatoid Arthritis (RA) in relation to smoking and HLA-DRB1 shared epitope; the two best known risk factors for RA and in addition, to perform subanalyses in patients where relations between variations in GSTM1 and RA have previously been described. This evidence concerns the gene HLA-DRB1 and rheumatoid arthritis.