Abstract: Objective: To study the role of vasoactive intestinal polypeptide like（VIP-LI） nerve fibers innervating middle cerebral artery （MCA） during cerebral ischemia.Methods: The model of rat focal cerebral ischemia was produced with the thread occlusion of the MCA. The dyamic changes of the number of VIP-LI nerve fibers in MCA were studied with the techniques of immunohistochemistry. Results: The denasity （the averaged number or nerve fibers in a unit area） of VIP-LI nerve fibers of MCA in the ischemic side decreased 24 hours after ischemia, returned to normal after 1 week, increased after 2 to 4 weeks and became normal again during the 5th week.Conclusion: The cerebral artery innervating VIP-LI nerve fibers may play a protective role during cerebral ischemia.