Abstract: AIM To study the effect of dl-3-n-butylphthalide (dl-NBP) on arachidonic acid(AA) release and phospholipase A2 (PLA2) mRNA in cerebral cortex of rats subjected to focal cerebral ischemia. METHODS Focal cerebral ischemia was induced by inserting a monofilament nylon suture into the internal carotid artery and blocking the origin of the middle cerebral artery. AA was determined with high performance liquid chromatography (HPLC). The PLA2 mRNA expression was evaluated by Northern blot analysis. RESULTS Six hours of cerebral ischemia induced AA release in the ischemic cerebral cortex. dl-NBP (10 or 20 mg·kg-1) and nimodipine (0.5 mg·kg-1) given intraperitoneally 5 min and 120 min again after the onset of ischemia significantly reduced AA concentration in the cerebral cortex (P<0.01). d-NBP, but not l-NBP, decreased AA release in the brain after middle cerebral artery occlusion. The expression of PLA2 mRNA in cerebral cortex induced by cerebral ischemia was also inhibited by dl-NBP and d-NBP (10 or 20 mg·kg-1, ip). CONCLUSION dl-NBP and d-NBP inhibited AA release and PLA2 mRNA expression in the ischemic brain tissue in vivo.