OBJECT: Impairment of endothelial nitric oxide synthase (eNOS), endothelium-dependent relaxation, and cerebrovascular autoregulation all occur in vasospastic cerebral arteries following subarachnoid hemorrhage (SAH). The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, both improve endothelial function and increase eNOS messenger RNA, protein, and enzymatic activity threefold. Increasing experimental evidence in animal models of SAH suggests that statins may ameliorate cerebral vasospasm. The authors hypothesized that patients chronically treated with statins would have a decreased risk of symptomatic vasospasm after SAH. METHODS: The authors retrospectively reviewed the charts of 115 patients with SAH who were consecutively admitted to the Neuroscience Intensive Care Unit of Duke University between 1998 and 2001. The independent association of statin therapy to symptomatic vasospasm was assessed using multivariate logistic regression analysis. Fifteen patients (13%) admitted with SAH were receiving statin therapy for at least 1 month before admission. Forty-nine patients (43%) experienced symptomatic vasospasm a mean of 5.8 +/- 3 days after onset of SAH. Current statin therapy on admission (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.01-0.77) was independently associated with an 11-fold reduction in the risk of symptomatic vasospasm. Fisher Grade 3 SAH (OR 2.82, 95% CI 1.50-5.71) and rupture of anterior cerebral or internal carotid artery aneurysm (OR 3.77, 95% CI 1.29-10.91) were independently associated with an increased risk of symptomatic vasospasm. CONCLUSIONS: In this retrospective case series, patients who received statin therapy for at least 1 month demonstrated an 11-fold decrease in the risk of developing symptomatic vasospasm after SAH.