Background: Quercetin-3-O-rhamnoside (QUE) has anti-inflammatory and anti-oxidative effects which probably beneficially used in lupus. Objective: This research was focused on analyzing the effects of QUE on FOXP3 modulation to result in an anti-inflammatory outcome in the kidney of severe lupus mice. Methods: This research used Pristane-induced female BALB/c lupus mice, and the biomarkers involved in were CD4 + CD25+ T reg cells, FOXP3 T cells, anti-Sm, IL-6, and histopathology assessment of the kidney of lupus mice. The QUE group was treated and compared to the negative control which received placebo, and the positive control which received cyclophosphamide. Results: QUE increased the number of CD4 + CD25 + T reg cells (negative control: 3.01±3.43%; QUE: 18.77±5.12%; positive control: 3.26±11.09%), and FOXP3 significantly (p<0.05) (negative control: 1.14±0.54%; QUE: 2.00±1.45%; positive control: 1.73±1.14%). The antiSm level did not decrease, meanwhile the IL-6 decreased significantly, and the histopathological assessment of the kidney reveal the repairing effects of QUE on glomeruli. Conclusion: QUE has an anti-inflammatory activity which reduces the severity of lupus nephritis signs in lupus mice by initially increasing the CD4 + CD25+ and FOXP3 + Tregs numbers. QUE is potential to be further developed as a safe treatment choice for lupus nephritis. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.