Moyamoya disease is a cerebrovasculopathy of unknown etiology during the course of which the main and terminal veins of the internal carotid artery undergo progressive vein occlusion. Leigh syndrome is a mitochondrial encephalomyopathy that occurs due to "cytochrome c oxidase deficiency" characterized by psychomotor retardation, difficulty in eating, seizures, hypotonia, respiratory disorders and high lactate levels. Many diseases and syndromes have been defined that are associated with Moyamoya disease. To the best of our knowledge, the association of moyamoya disease with Leigh syndrome has not been defined as yet. In this study, the clinical and imaging results of a 3-year-old male child displaying the association of Moyamoya disease and Leigh syndrome are presented.