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Background: One of the environmental factors leading to Alzheimer's disease (AD) is traumatic brain injury (TBI). Meanwhile, tau protein hyperphosphorylation is known as one of the mechanisms of AD development. In the present study, the effect of Rosa damascena and Ginkgo biloba aqueous extracts on tau hyperphosphorylation was studied on SH-SY5Y cell lines and mouse TBI models. Methods: Tau protein hyperphosphorylation was induced in SH-SY5Y cells using 10 μM retinoic acid (RA). Then, cells were treated with 500 and 1000 μg/ml aqueous extracts of Rosa damascena and Ginkgo biloba. Cell viability was studied by MTT test and tau protein hyperphosphorylation was studied by western blot and immunostaining techniques. Also, after the induction of TBI by pneumatic cylinder, mice were treated with 500 and 1000 μg/ml aqueous extracts of Rosa damascena and Ginkgo biloba, and the animals were tested for beam balance and walk tests to measure balance and muscle stiffness. Finally, tau protein hyperphosphorylation in the brain was investigated using an immunostaining technique. Results: Both aqueous extracts of Rosa damascena and Ginkgo biloba were able to improve SH-SY5Y viability. Also, a decrease in phosphorylated tau protein was observed in cells treated with aqueous extracts of Rosa damascena and Ginkgo biloba. Performance improvements in beam balance and walk tests in TBI mice treated with 1000 μg/ml Rosa damascena and Ginkgo biloba aqueous extracts were seen. Also, tau protein phosphorylation was significantly decreased in the brain of TBI rats treated with those aqueous extracts. Conclusion: aqueous extracts of Rosa damascena and Ginkgo biloba have neuroprotective effects and are beneficial in reducing TBI-induced tau protein hyperphosphorylation, and they can prevent tau pathology. [ABSTRACT FROM AUTHOR]