Objective: Severe angiographic vasospasm (aVSP) is a risk factor for poor functional outcome following subarachnoid hemorrhage. We investigated the impact of angiographic surveillance and intensive endovascular treatment using transluminal balloon angioplasty (TBA) and/or verapamil infusion for severe aVSP through comparison of clinical outcomes in patients of similar presenting grade but with no/mild vasospasm. Methods: This was an analysis of prospectively acquired clinical trial data. World Federation of Neurosurgical Societies (WFNS) grade 1-2 patients presenting within 72 h were included. Angiographic screening for vasospasm was undertaken at days 5-7 or in response to clinical deterioration. Severe aVSP was defined as >50% luminal narrowing on digital subtraction angiography. Treatment was instituted on the basis of radiographic findings and/or clinical deterioration. Discharge destination and favorable clinical outcomes (discharge Glasgow Outcome Score (GOS) 4-5, 90 day modified Rankin Scale (mRS) score 0-2, and GOS 4-5) for patients with severe aVSP were compared with those without significant vasospasm. Statistical analysis was undertaken using Fisher's exact test. Results: 63 WFNS grade 1-2 patients with minimal vasospasm were compared with 17 WFNS grade 1-2 patients with severe aVSP treated with induced hypertension and endovascular therapy. Results: were available in 62 and 16 patients, respectively. Rates of favorable outcome did not differ significantly between the two groups. For patients with treated severe vasospasm, 90 day mRS 0-2 was seen in 15/17 (88.2%) and GOS 4-5 was achieved in 16/17 (94.1%). Conclusions: An intensive endovascular approach of TBA and/or intra-arterial verapamil in combination with induced hypertension for severe aVSP may result in comparable clinical outcomes to those without vasospasm.