BACKGROUND: Intracranial stenosis in young patients appears to have different characteristics from that observed in the older population. OBJECTIVE: To study the differences in the pathogenesis of intracranial stenosis in younger patients as compared to the older population. METHODS: The clinical characteristics of patients with angiographically confirmed intracranial stenosis were matched to a healthy population using the National Health and Nutrition Examination Study (NHANES). The study population was stratified into two age groups (=45 and >45 years). The relative risk (odds ratios) and attributable risk of known cardiovascular risk factors were estimated. RESULTS: A total of 17 (11%) patients from 153 patients with intracranial stenosis were aged =45 years. These patients were more likely to be women (53 vs. 28%, p < 0.05). The location of the lesion in the young patients was more likely to be in the internal carotid artery (65 vs. 29%, p < 0.05). When compared with the stroke risk factors from the NHANES control population, the attributable risk of hypertension, diabetes mellitus, and coronary artery disease for intracranial stenosis was lower among patients aged =45 years than that for patients aged >45 years (6.4 vs. 13.1%, 19.9 vs. 33.0% and 1.0 vs. 10.8%, respectively). Hyperlipidemia had a greater attributable risk of intracranial stenosis in patients =45 than in those >45 years of age (23.3 vs. 9.3%). CONCLUSIONS: Intracranial stenosis in young patients is predominantly located in the anterior circulation and more frequently occurs in young women. Even though the stroke risk factors appear to be strongly associated with intracranial stenosis in this age group, the impact of these risk factors is low due to the low prevalence.