Abstract: Objective To study the effect of Toll-like receptor 4 (TLR4) inhibitor E5564 on delayed cerebral vasospasm (DCV) following subarachnoid hemorrhage (SAH). Methods Sixty New Zealand rabbits were randomly divided into SAH model group, control group and E5564 group (20 in each group). Blood was injected into the animal cisterna magna of SAH model group, saline was injected into the animal cisterna magna of control group, and E5546 was injected into the animal vein of E5564 group after the SAH model was established. DCV was assessed by angiography and TCD, respectively. Basilar artery spasm was observed with HE staining 7 days after the SAH model was established. Expression of TLR4 in basilar artery was detected by immunohistochemistry and Western blot, respectively. Results The diameter of basilar artery was significantly shorter in SAH model group than in control group and signifcantly longer in E5564 group than in SAH model group (P＜ 0.01). Immunohistochemistry and Western blot showed that the expression level of TLR4 in basilar artery was significantly lower in E5564 group than in SAH model group (P＜ 0.05). Conclusion DCV following SAH may be associated with the TLR4 signal pathway. E5564 can signifcantly inhibit the expression of TLR-4 in basilar artery, thus alleviating DCV following SAH.