BACKGROUND AND PURPOSE: Intracranial large-artery atherosclerosis is considered a frequent cause of stroke worldwide, particularly in Asian populations. The current evidence suggests that symptomatic patients with severe stenosis may benefit from intracranial stents. There are two methods for calculating the degree of intracranial stenosis, Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) and North American Symptomatic Carotid Endarterectomy Trial (NASCET), but they have never been compared. METHODS: A total of 25 patients with suspected middle cerebral artery (MCA) stenosis based on their acute presentation were imaged by computed tomography angiography (CTA), then confirmed by digital subtraction angiography (DSA). Measurements were carried out on symptomatic MCA using both methods for determining the degree of stenosis. RESULTS: The degree of stenosis was significantly different using NASCET and WASID methods in DSA (48.2% vs. 54.6%; P<0.01), whereas CTA values did not differ significantly (54.2% vs. 52.0%; P=0.9). All measurements were highly correlated between methods (Spearman r=0.92 and 0.89, respectively; P<0.01). CONCLUSION: The results of this study suggest that NASCET and WASID measures are, on average, generally similar, although substantial disagreement in a given patient may be seen.