Background: Lupus nephritis (LN) is an inflammation of the kidney that is one of the most seri-ous complications of SLE. Recent studies revealed that the Foxp3 plays an important role in the pathogenesis of SLE. Objectives: To measure Foxp3 mRNA expressions in peripheral blood of patients with active and inactive form of lupus nephritis (LN) versus healthy control subjects and explore its role in disease activity. Subjects and Methods: Real time PCR was used to detect the mRNA expression of Foxp3 by SYBR Green technique in the peripheral blood mononuclear cells (PBMNCs Foxp3) of 24 patients with active lupus nephritis (LN), 10 patients with inactive lupus and 40 healthy subjects. Results: We found that Foxp3 mRNA expression level in both patient groups (n=34) was significantly higher than that in normal control group (n=40), (p < 0.05). The mRNA expression of Foxp3 inactive stage (n=24) was higher than that in inactive stage (n=10), (p < 0.05). Moreover, Foxp3 mRNA level positively correlated with SLEDAI (r=0.592, p