Abstract: Background 5-lipoxygenase（5-LO）catalyzes arachidonic acid to leukotrienes which involved in complicated interactions between atherosclerosis and invading inflammatory cells.Objective To investigate 5 LO expression in cerebral artery and test the speculation that 5-LO is associated with BP elevation in SHR.Methods The 5-LO expression distribution was detected by immunofluorescence and Western blot,and the level of ＆LO ex- pression was compared in spontaneous hypertensive rat（SHR）and Wistar-kyoto（WKY）rat at 5 weeks,16 weeks and 28 weeks old.Results 5-LO was expressed in rat cerebral smooth muscle cells,and mainly located in cyto- plasm.In 5,16,28 weeks when the BP was elevated in SHR,the levels of 5-LO were increased by 2%（P＞ 0.05）,20%（P＜0.05）and 39%（P＜0.01）respectively,compared with the matched age WKY rats.Using 5-LO at 5th weeks of age as reference,the 5-LO expression in cerebral arteries at 16th weeks were increased to 115%（P＜0.05）,at 28th weeks to 141%（P＜0.05）.Conclusion Our data shows 5-LO was expressed in smooth muscle cell of cerebral artery,and was progressively increased with the age of SHR.The expression of 5-LO in the cerebral artery of SHR is greater than that in WKY.