According to our analysis, RRM2 was significantly up-regulated in synovial tissue and peripheral blood of RA suffers, having a good performance as a the diagnostic marker (the AUC was 0.937 and 95% CI: 0.839–1.000 in the merged GSE55235 and GSE55457; the AUC was 0.929 and 95% CI: 0.786–1.000 in the GSE77298; the AUC was 0.689 and 95% CI: 0.599–0.775 in the GSE93272). This evidence concerns the gene RRM2 and rheumatoid arthritis.