To elucidate the relationship between metabolic syndrome (MetS) and cerebrovascular stenosis, we performed comparative studies of MetS and its components between ischemic stroke patients with intra- and extracranial atherostenosis. We evaluated 378 acute ischemic stroke patients who underwent brain magnetic resonance (MR) imaging and MR angiography. Stenosis was diagnosed in cases showing a degree of luminal narrowing of > or = 50%. The stroke subtypes were categorized as large artery atherosclerosis (LAA), small artery occlusion (SAO), cardioembolism (CE), and stroke of undetermined etiology (SUE). MetS was defined using the criteria of the Adult Treatment Panel III. The mean carotid intimal medial thickness values showed increased tendency as the number of MetS components increased (P < 0.001). Regardless of stroke subtype, the MetS (+) group showed an increasing tendency toward stenosis (LAA, SAO, all P < 0.001; CE, P = 0.001; SUE, P = 0.077). MetS was independently associated with intracranial atherosclerosis (odds ratio, 3.58; 95% CI, 2.28-5.63), which was prominent with more severe MetS components after adjustment for other risk factors (P < 0.001). Amongst the component conditions, elevated blood pressure, increased blood glucose/hyperglycemia, and abdominal obesity were dominantly associated with stenosis (all P < 0.001). Modifications of the individual MetS components need to be considered for stroke prevention because of intracranial atherogenic progression.