Many institutes and clinics have been involved these 20-30 years in trying to clarify cerebral vasospasm after SAH. However neither cause nor therapy have yet been clearly identified. We reviewed the updated progress of research for origin of vasospasm updated. It consists of mechanical stimulation, vasoactive substances in the CSF, denervation supersensitivity of the cerebral vessels, structural changes of the vessel wall and inflammation. We also reviewed progress of the therapy for vasospasm. Therapeutic method was divided into two groups, those that use drugs to resolve vasospasm and those that don't. The former group is made up of numerous number ofvasodilating drugs, free radical scavengers, thromboxane A2 synthesis blockers and cerebral protection agents. The latter group uses clot removal during operation, hypertensive and hypervolemic therapy and so on. Every time Iencounter cases involved by symptomatic vasospasm after SAH, I feel the limitation of our therapeutic ability. It isto be hoped that we neurosurgeons can overcome cerebral vasospasm in the not too distant future.