To explore the mechanism of action of butylphalide (NBP) against the injury following oxygen glucose deprivation/reoxygenation (OGD/R) in rat cortical neurons, neurons of Wistar newborn rats were prepared by filtering through a mesh, centrifugation and trypsogen digestion. A simple, stable and reliable in vitro model of OGD/R of neurons was established. We studied the activation, the nuclear translocation of NF-kappaB p65 and the mRNA expression of iNOS affected by NBP in each group neuron by RT-PCR. NBP is proved to be able to add cellular vigor and decrease LDH release. The mRNA expression of iNOS in neurons after OGD 4 h/R 8 h decreased when treated with NBP. There is statistical difference between each concentration of NBP that it adds cellular vigor, decreases LDH release and expression of iNOS in neurons after OGD 4 h/R 8 h. There is also statistical difference between NBP (100 micromol x L(-1)) and PDTC (100 micromol x L(-1)). It is proved that NBP can protect neurons, block upregulation of iNOS mRNA, and restrain activation of NF-kappaB in neurons.