Endovascular procedures for treating delayed cerebral vasospasm after subarachnoid hemorrhage are widely used. Endovascular therapy should be attempted in patients with symptomatic vasospasm refractory to hemodynamic augmentation. This chapter reviews the indications for transluminal balloon angioplasty and intra-arterial administration of calcium channel blockers along with periprocedural medical management of these tenuous situations. Intra-arterial infusion of calcium channel antagonists is effective to improve vasospasm in most patients but has a short-lived effect. Balloon angioplasty is the most effective treatment for proximal large artery vasospasm and has a more durable effect but cannot treat vasospasm of the distal circulation.