Background and purpose Along with intracranial atherosclerotic disease (ICAD), moyamoya disease (MMD) is the most common cause of middle cerebral artery (MCA) occlusion in Asians. Although they have differing vascular wall pathologies, conventional angiographic evaluation methods cannot easily differentiate MMD from ICAD in certain situations, such as in young patients with atherosclerotic risk factors. High resolution magnetic resonance imaging (HR‐MRI) findings for the diseased segments of MCAs in MMD and symptomatic ICAD were compared to further elucidate differences in arterial wall changes. Methods Angiographically confirmed patients, 12 MMD and 20 ICAD, who suffered a stroke due to MCA occlusion were recruited and underwent HR‐MRI. The size of the outer diameter and other stenotic vessel wall characteristics revealed by HR‐MRI, including enhancement, eccentricity and other lesion patterns, were analyzed by two independent reviewers in a blind fashion. Results MMD patients were younger than ICAD patients (32.92 ± 11.08 years vs. 51.85 ± 11.97 years; mean ± SD) and displayed a smaller outer diameter in the stenotic portion (1.61 ± 0.43 mm for MMD vs. 3.03 ± 0.53 mm for ICAD, P < 0.0001). Eccentric lesions (three of 12 in MMD vs. 19 of 20 in ICAD, P < 0.0001) and focal enhancements in diseased areas (two of seven in MMD vs. 13 of 17 in ICAD, P = 0.061) were less common in MMD cases. Conclusions Our HR‐MRI findings show that MMD is associated with smaller, concentric occlusive lesions which are rarely enhanced compared with symptomatic ICAD, consistent with the results of previous pathological reports. HR‐MRI may therefore have utility in differentiating MMD from ICAD.