The current study aims to highlight the biomarkers toxicity that may be linked to the bioaccumulation of aluminum (Al) in some regions of the brain (cortex, cerebellum, and hippocampus) of male albino rats, after intranasal instillation of aluminum oxide nanoparticles (Al₂O₃NPs). To achieve this goal, rats were divided into two groups. By intranasal dripping, rats of the first group were given deionized water, whereas rats of the second group were given 0.9 g of Al₂O₃NPs (0.9 mg/kg/2) every two days. The results indicated that the bioaccumulation of Al has been significantly affected by the experimental periods (2, 8, 14 and 20 days) and brain regions. Bioaccumulation of Al in the cortex is much higher than in the cerebellum and hippocampus, at all the experimental periods. On the other hand, Al levels in rats of the second group were significantly higher than their corresponding levels in comparison with the first group, in the three brain regions. Regression analysis affirmed that there is a direct positive relationship of the experimental periods with the levels of Al, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), but that relationship was negative with the glutathione (GSH) levels. In addition, there was a positive relationship between the accumulated Al, in the three brain regions, with the levels of MDA and H₂O₂, but that relationship was negative with the GSH. Levels of GSH were negatively correlated with the concentrations of MDA and H₂O₂. In conclusion, Al₂O₃NPs are highly bio-accumulative and selective for different brain regions and this accumulation caused a marked increase in the liberation of H₂O₂ into the brain tissues and potentiated the oxidative stress.