Background: Recent studies have demonstrated that many nanoparticles have an adverseor toxic effect on the kidney.Objective: To investigate the nephroprotective effect of quercetin (QT) against renal injuryinduced by titanium dioxide nanoparticles (NTiO2) in rats.Methods: NTiO2-intoxicated rats received 50 mg/kg of NTiO2 for seven days. The QT +NTiO2 group was pretreated with QT for seven days before being administered NTiO2. Uric acid,creatinine, and blood urea nitrogen were considered to be biomarkers of nephrotoxicity. Catalase(CAT) and superoxide dismutase (SOD) activities and renal levels of malondialdehyde (MDA) weremeasured to assess the oxidative stress caused by NTiO2.Results: NTiO2 significantly increased the plasma level of the biomarkers. It alsosignificantly decreased the activities of CAT (P = 0.008) and SOD (P = 0.004), and significantlyincreased the MDA levels (P = 0.007). NTiO2 caused proximal tubule damage, the accumulationof red blood cells, the infiltration of inflammatory cells, and reduced the glomerular diameters,as well as induced apoptosis in the proximal tubules. Pre-treatment with QT attenuated thehistological changes, normalised the plasma biomarkers, suppressed oxidative stress, amelioratedthe activities of CAT (P = 0.007) and SOD (P = 0.006), and reduced apoptosis (P < 0.001).Conclusion: QT was found to have a potent protective effect against nephrotoxicityinduced by NTiO2 in rats. It also reduced apoptosis caused by NTiO2.