〔Abstract〕 Objective To investigate the expression of T cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory domains( TIGIT) on peripheral natural killer( NK) cells from patients with rheumatoid arthritis( RA) and its significance and to clarify its relation in the development of RA. Methods The peripheral blood mononuclear cell( PBMC) from 33 patients and 27 healthy controls( HCs) were collected and TIGIT expression in the NK cells were detected by flow cytometry. The correlations of TIGIT expression on NK cells with clinical data were analyzed. Student't test or Mann-Whitney U test was used for comparison between the two groups,and the correlation between the two variables was analyzed by Pearson or Spearman correlation. Results(1) The percentage of NK cells and NK cells counts were significantly decreased in RA patients compared to the HC( P = 0. 005 1; P<0. 000 1);(2) The expression mean fluorescence intensity( MFI) of TIGIT on NK cells was significantly decreased in RA patients compared to the HC( P<0. 000 1);(3) The expression MFI of TIGIT on NK cells in RA patients was found to negatively correlate with CRP( r =-0. 346 3,P = 0. 048 4);(4) MFI of TIGIT expression in NK cells of RA patients is negatively correlated with rheumatoid factor( RF) and positive RF( r =-0. 360 7,P =0. 042 6; r =-0. 400 5,P = 0. 047 3);(5) The expression MFI of TIGIT on NK cells was significantly lower early RA patients than in non-early RA patients( P = 0. 038 5). Conclusion The expression MFI of TIGIT on NK cells is decreased and associated with the inflammation markers,the production of antibodies in RA.