If patients are treated within the first 3 days after rupture, early definitive clipping associated with mechanical clot removal to the extent practical and instillation of fibrinolytic agents seems likely to become standard therapy. Patients should also receive calcium antagonists and be maintained in normal fluid and electrolyte balance. At the first sign of delayed ischemic deficits, therapy with hypervolemia and hypertension should be instituted. If clinical deterioration is progressive despite this, consideration should be given to intra-arterial vasodilators or balloon angioplasty. If patients are referred more than 3 days after hemorrhage, we still advocate the same course of action unless the patient presents with established severe diffuse vasospasm and is unconscious. Operation in such a setting is likely to be associated with prohibitive mortality and morbidity. In such cases, it might be worth the risk of using intra-arterial vasodilators or balloon angioplasty despite the presence of an unclipped aneurysm. The last decade has witnessed substantial advances in our knowledge of the pathogenesis of vasospasm and we now have a reasonable chance at effective prophylaxis and treatment.