Objective To investigate the relationship between the single nucleotide polymorphisims in pre-miR-146a rs2910164 and miR-146a expression in rheumatoid arthritis(RA).Methods Polymerase chain reaction- ligation detection reaction (PCR-LDR) was used to detect the pre-miR-146a rs2910164 single nucleotide polymorphisms in 123 patients with rheumatoid arthritis (RA) and 220 healthy controls.Expression of miR-146a in peripheral blood mononuclear cells was studied using quantitative realtime polymerase chain reaction (qRT-PCR) in 68 RA patients,10 osteoarthritis (OA) patients and 20 healthy controls.After application of glucocorticoid and NSAIDS combined with DMARDS for three months in 10 patients with active RA,miR-146a expression was again analyzed by qRT-PCR.Clinical characteristics including sex,age at onset,rheumatoid factor (RF),anti-cyclic citrullinated peptide (anti-CCP) antibody,RA activity (DAS28 ≥3.2) and bone erosion (X-ray ＞ Ⅰ stage) were taken into account.X2 test,One-Way ANOVA,t test and Pearson correlation were used for statistical analysis.Results The polymorphisms of the pre-miR-146a rs2910164 were not correlated with susceptibility to RA (P＞0.05).There were no associations between pre-miR-146a rs2910164 genotypes and sex,age at onset,status of RF and antiCCP,RA activity,bone erosion and miR-146a expression in RA patients (P＞0.05 for each).MiR-146a expression was significantly higher in RA patients than that in OA patients and that in healthy controls( P＜0.01 for each) but did not differ between the latter two groups (P＞0.05).MiR-146a expression was significantly higher in active RA patients than that in inactive patients and that in healthy individuals (P＜0.01 for each).After treatment,miR-146a expression and DAS28 score were lower obviously (P＜0.05,P＜0.01,respectively).MiR-146a expression was positively correlated to ESR,CRP and DAS28 score (P＜0.01 for each),but not to RF titer and anti-CCP antibody titer (P＞0.05 for each).Conclusion The polymorphisms of the pre-miR-146a rs2910164 are not associated with susceptibility to RA,and not correlated with clinical characteristics and miR-146a expression in RA patients.MiR-146a expression is upregulated in patients with RA,and may be a potentially useful marker of disease activity in these patients.