The brain MR images of 23 patients with angiographically proved moyamoya disease were reviewed to evaluate the capability of MR to demonstrate vascular and parenchymal abnormalities. All the MR images were obtained on a 2.0 T superconducting system and included T1-weighted sagittal and T2-weighted axial images without implementation of flow compensation (FC). The vascular abnormalities demonstrated on MR images were narrowing of the cavernous internal carotid artery (ICA) (73%), narrowing or occlusion of the supraclinoid ICA (87%) and proximal middle cerebral artery (MCA) (91%), and multiple collateral vessels in the basal ganglia and/or thalamus (96%). The parenchymal abnormalities included ischemic infarctions (74%), predominantly located in watershed areas, hemorrhagic infarctions (26%), intracerebral hematomas (13%), and intraventricular hemorrhage (13%). In conclusion, MR imaging was a useful diagnostic modality for detecting both vascular and parenchymal abnormalities associated with moyamoya disease. This may obviate the need for invasive angiography as far as the diagnosis is wanted at the non-quantitative level.