To establish management protocol for delayed ischemic deficits(DID), the authors designed a prospective study involving patients with aneurysmal subarachnoid hemorrhage, Fisher group 2 or 3, who had been admitted within 72 hours of the first rupture. The study group consisted of 100 consecutive surgical cases who underwent prophylactic hyperdynamic therapy during the period May 1995 to December 1996. The historical control group was a series of 117 patients, treated between January 1993 and April 1995, who did not undergo the same therapy. DID occurred in seven of 51 patients(13.7%) in the study group who underwent surgery within 72 hours of the first rupture, and in ten of 38 patients(26.3%) in the control group who similarly under surgery. Patients who postoperatively showed evidence of DID were managed as follows ; 1) in those developing DID without increased velocity on transcranial Doppler(TCD) study, hypertension was induced ; 2) in those who on TCD study showed increased flow velocity, cerebral angiography was performed ; 3) those with significant arteriographic vasospasm or delayed cerebral circulation, were intra-arterially infused with papaverine. In conclusion, prophylactic hyperdynamic therapy is an effective tool for the prevention of DID, especially following early surgery. TCD study may not effectively detect DID, but is a useful guide to the selection of management modalities. Intra-arterial papaverine infusion is an effective therapy for angiographic vasospasm and the prevention of DID.