Abstract: Objective To explore the diagnostic value of MiR-485-3p in IgA nephropathy (IgAN)and examine its correlation with IgA/C3 and CD4+/CD8+. Methods From January 2018 to December 2020, 106 IgAN patients(IgAN group), 90 non-IgA nephropathy patients with primary glomerulonephritis(non-IgAN group)and 50 normal subjects(control group)were selected. The levels of MiR-485-3p, immunological parameters(IgA, IgG, IgM, C3, C4 & IgA/C3)and T lymphocyte subsets(CD4+, CD8+ & CD4+/CD8+)were measured. Multivariate Logistic regression was employed for examining the risk factors for IgAN. And receiver operating characteristic(ROC)curve was plotted for analyzing the diagnostic values of miR-485-3p, IgA/C3 and CD4+/CD8+ for IgAN. The correlations between miR-485-3p expression level and IgA, IgG, IgM, C3, C4, IgA/C3, CD4+, CD8+ and CD4+/CD8+ were analyzed by Pearson's correlation. Results IgAN group miR-485-3p (0.48±0.06 vs 1.20±0.25, 1.96±0.73), CD4+(31.46±6.82)% vs(42.15±8.40)%, (47.50±9.35)%and CD4+/CD8+(1.02±0.46 vs 1.50±0.71, 1.63±0.58)were significantly lower than those in non-IgAN and control groups(P<0.001). Levels of IgA(3.16±1.18) g/L vs(2.05±0.73) g/L, (1.24±0.46)g/L and IgA/C3(2.94±1.05 vs 1.81±0.86, 1.13±0.52) were significantly higher in IgAN group than those in non-IgAN and control groups(P<0.001). Multivariate Logistic regression analysis revealed that high levels of urinary protein, IgA/C3 and low levels of eGFR, CD4+/CD8+ and miR-485-3p were risk factors for IgAN(P<0.05). ROC curve results indicated that AUC of serum expression level of miR-485-3p in the diagnosis of IgAN was 0.862(95%CI:0.803-0.922); AUC of miR-485-3p plus IgA/C3 and CD4+/CD8+ in the diagnosis of IgAN was 0.937(95%CI:0.878-0.995), sensitivity 96.3% and specificity 84.2%. Correlation analysis showed that serum expression level of miR-485-3p was correlated negatively with IgA and IgA/C3(r=-0.753, -0.827, P<0.05) and positively with CD4+, CD4+/CD8+(r=0.435, 0.692, P<0.05)in IgAN group. Conclusion The expression of miR-485-3p is low in IgAN patients. It is correlated with IgA/C3 and CD4+/CD8+ and combining three items has a high diagnostic value for IgAN.