Abstract： Objective To investigate the effect of erythropoietin (Epo) on tau hyperphosphorylation induced by β-amyloid peptide 25-35 (Aβ25-35) in SH-SY5Y cells. Methods MTT assay was employed to identify the changes in the viability of SH-SY5Y cells following Epo treatment at 0, 5, 10, 20, and 50 U. Western blot was used to detect the levels oftau phosphorylation at Ser396, Ser199 and Taul at different time points after treatment with 20 μmol/L Aβ25-35. The effect of a 3-hour EPO pretreatment at 5, 10, and 20 U on the actions of Aβ25-35 was evaluated. The inhibitory effect of Epo on Aβ25-35-induced neurotoxicity after pretreatment with the PI3K/Akt inhibitor LY294002 was assessed to explore the possible mechanism of Epo. Results The viability of SH-SY5Y cells showed no obvious changes in response to Epo exposure at different doses. Western blot showed that Aβ25-35 induced increased phosphorylation at Ser396 and Ser199 3 hatter the treatment. The phosphorylation reached the peak level at 6 h after Aβ25-35 treatment and gradually decreased after 12 h, but stilled maintained a significantly higher level at 24 h,compared with 0 min, 30 min (P<0.05). The total tau underwent no significant changes in response to Aβ25-35 treatment (P>0.05). Epo pretreatment at 5, 10, and 20 U efficiently inhibited Aβ25-35-induced tau phosphorylation in comparison with that in the control cells(P<0.05), and application of LY294002 resulted in obvious inhibition of the effect of Epo. Conclusion Epo can inhibit Aβ25-35-induced tau phosphorylation via PI3K/Akt signaling pathway, and this finding provides an important theoretical basis for studying the pathogenesis and management of AD.