Abstract: The effects of 3-n-butylphthalide(NBP) on the levels of 6-keto-PGF_1α,TXB₂ and 6ketoPGF_1α/TXB₂ ratio were studied with methods of RIA.d-NBP and l-NBP(0.1～100μmol·L^-1) concentrationdependently increased 6-keto-PGF_1α release, decreased TXB₂ release from neuronal cells, and significantly enhanced extracellular 6-keto-PGF_1α/TXB₂ ratio in primary cultured rat cortical neurons exposed　to hypoxichypoglycemic media for 5 h or hypoxic-hypoglycemic media for 5 h following normal media for 3 h. Aspirin(0.1～100μmol·L^-1) was also shown to inhibit TXB₂ release from cortical neurons in a dose-dependent manner. However aspirin only increased 6ketoPGF_1α/TXB₂ ratio at low dose because aspirin inhibited both 6-keto-PGF_1α and TXB₂ release simultaneously at large dose(10～100 μmol·L^-1). This suggests that the action of l-NBP, d-NBP and dl-NBP on the increase of 6-keto-PGF_1α/TXB₂ ratio might be one of the mechanisms in which NBP enhanced focal cerebral blood flow and improved ischemic brain damage.