Abstract: Effects of dl-3nbutylphthalide(dl-NBP) on changes of regional cerebal blood flow (rCBF) and blood-brain barrier of rats subjected to subarachnoid hemorrhage (SAH) were investigated. Regional CBF was determined by hydrogen clearance method at 15 min before, 15 and 30 min thereafter once every 30 min up to 180 min after the beginning of SAH. The results showed that SAH produced a significant decrease in rCBF in caudate nucleus and blood-brain barrier damage which displayed increased extravasation of Evans blue to brain tissue. Both dl-NBP (5～20 mg·kg^-1 given intraperitoneally 5 min after the onset of SAH) and nimodipine (0.25 mg·kg^-1) were shown to increase rCBF in caudate nucleus through 3 h of SAH. Moreover, dl-NBP 10 mg·kg^-1 and nimodipine 0.25 mg·kg^-1, given 5 min and 3 h, respectively, after SAH, significantly reduced the brain extravasation of Evans blue 6 h after SAH, indicating that both dl-NBP and nimodipine has protective effects on bloodbrain barrier. These results suggest that dl-NBP has therapeutic effects on SAH.