Moyamoya disease is known to be an important pathogenesis of cerebral infarction and polymicrogyria is characterised by abnormalities in migration of neurons to the cortex. Neuronal migration disorder is rarely accompanied by vascular abnormalities. Although previous reports have suggested that cortical developmental anomaly might be associated with arterial dysplasia, no cases associated with moyamoya disease have been demonstrated. We report a rare case of polymicroyria in a patient with moyamoya disease. Key words: Moyamoya disease; Polymicrogyria; Malformation of cortical development