Anatomical pathology consists an important basis for the understanding of pathogenesis. Anatomicopathological changes of stenosed arterial wall of moyamoya disease (MMD) include eccentric fibrocellular thickening of intima with abundant smooth muscle cells inside, waving torturosity in the internal elastic lamina which was often duplicated, and thinning of the medial smooth muscle layer. Though the intima was thickened, high-resolution magnetic resonance imaging showed that the outer diameter of middle cerebral artery was diminished. Most of the moyamoya vessels presented dilated changes, including luminal dilation and mural thinning, while severely dilated ones presented thinning or dissecting of internal elastic laminas, even microaneurysms. Some moyamoya vessels, such as perforating arteries close to diseased trunks, presented stenotic changes similar to those of stenosed main trunks. Future breakthrough in pathological studies of MMD arterial depends on the access to arterial wall samples from patients or development of animal models.