Recent studies have shown that microRNAs play an important role in autoimmune diseases. In this study, we studied the plasma expressive levels of miR-21, miR-126 and miR-148a in 44 patients with lupus nephritis (LN) and 24 healthy controls, and their clinical relationships were further analyzed. Compared with the healthy controls, plasma miR-21, miR-126 and miR-148a levels were significantly higher in LN patients. Receiver operating characteristic curve analysis of plasma miR-21, miR-126a and miR-148a showed that the areas under curve were 0.807 +/- 0.051 (P < 0.0001), 0.788 +/- 0.053 (P < 0.0001) and 0.776 +/- 0.055 (P = 0.0002), respectively, when differentiating LN patients from healthy controls. Plasma miR-21 levels were significantly negatively correlated with complement factors C3 (r = -0.420, P = 0.005), C4 (r = -0.362, P = 0.016), white blood cell (r = -0.395, P = 0.008) and red blood cell counts (r = -0.357, P = 0.017) and positively correlated with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) in patients with LN (r = 0.472, P = 0.001). In contrast, plasma miR-126 and miR-148a levels were not significantly correlated with any clinical data in our patient cohort. Therefore, our findings suggest that significantly increased plasma levels of miR-21, miR-148a, and miR-126 occur in LN patients, and plasma miR-21 levels are associated with C3 and C4 levels and the SLEDAI. The potential of circulating miR-21 as a non-invasive biomarker in LN patients warrants further study.