Background: The metabolic syndrome (MetS) is a cluster of risk factors linked to insulin resistance that increase an individual’s risk of atherosclerotic vascular disease. The authors evaluated the prevalence and prognosis of the MetS among individuals with symptomatic intracranial arterial stenosis. Methods: Patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease trial were evaluated in this post-hoc analysis. Baseline characteristics and outcome were compared in patients with the MetS vs patients without the MetS. Results: Among 476 patients, the prevalence of the MetS was 43%. MetS patients were more likely to be younger, female, and white. During a mean follow-up period of 1.8 years, time to the first of ischemic stroke, myocardial infarction, or vascular death was shorter among patients with the MetS with a hazard ratio (syndrome/no syndrome) of 1.6 (95%CI = 1.1 to 2.4, p = 0.0097). Time to ischemic stroke alone was also shorter among patients with the MetS with a hazard ratio (syndrome/no syndrome) of 1.7 (95%CI = 1.1 to 2.6, p = 0.012). When controlling for individual factors of the definition, MetS was not significant (combined outcome: p = 0.14; ischemic stroke: p = 0.074). Conclusions: The metabolic syndrome is present in about half of individuals with symptomatic intracranial atherosclerotic disease and is associated with a substantially higher risk of major vascular events. The metabolic syndrome may not provide additional ability to predict outcomes beyond the individual factors for patients with intracranial stenosis. The authors evaluated the prevalence and prognosis of the MetS among individuals with symptomatic intracranial arterial stenosis. Methods: Patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease trial were evaluated in this post-hoc analysis. Baseline characteristics and outcome were compared in patients with the MetS vs patients without the MetS. Results: Among 476 patients, the prevalence of the MetS was 43%. Meta patients were more likely to be younger, female, and white. During a mean follow-up period of 1.8 years, time to the first of ischemic stroke, myocardial infarction, or vascular death was shorter among patients with the MetS with a hazard ratio (syndrome / no syndrome) of 1.6 (95% CI = 1.1 to 2.4, p = 0.0097). Time to ischemic stroke alone was also shorter among patients with the MetS wi When controlling for individual factors of the definition, MetS was not significant (combined outcome: p = 0.14; ischemic stroke: p = 0.074). Conclusions: The metabolic syndrome is present in about half of individuals with symptomatic intracranial atherosclerotic disease and is associated with a substantially higher risk of major vascular events. The metabolic syndrome may not provide additional ability to predict outcomes beyond the individual factors for patients with intracranial stenosis.