Objective：To explore the protection of edaravone on acute cerebral vasospasm（CVS） after subarachnoid hemorrhage（SAH） in rats and effects of edaravone on expressions of serum S100B and endothelin-1（ET-1）. Methods：Totally 60 Wistar rats were randomly assigned to four groups：control group（group C），normal saline group（group N），simple group of SAH（group SAH） and group of SAH+ edaravone（group SAH+E）. CVS model after SAH was made by injecting rats’ own blood into cisterna twice. Microscopic im－age analysis was used to measure the basal artery diameter and ELISA was employed to determine S100B and ET-1serum levels pre－operatively in group C and at 6，24，72 h postoperatively in others groups. Results：Postoperative basilar artery diameters at the same time were in the following order（from small to large）：group SAH，group SAH + E，group N and group C. There was no statistically significant difference between groups N and C and the differences were statistically significant between the other groups. Factorial anal－ysis suggested that different treatments exerted different effects on the results. Basilar artery spasms sustained for 72 h. At the same time after operation，serum S100B and ET-1 levels were in the following order（from high to low）：group SAH，group SAH+E，group N and group C. There were statistically significant differences between groups but there was no difference between groups N and C. Fac－torial analysis suggested that different treatments exerted different effects on the results. Serum S100B and ET-1 increased consis－tently within 72 h，with statistically significant differences（P<0.05）. Conclusions：Serum S100B and ET-1 levels related with acute CVS after SAH. Edaravone can make serum S100B and an ET-1 level back to normal and thus plays a controlling role in improving acute CVS after SAH.