Stroke-like episodes have most frequently been reported in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), a multisystemic syndrome associated with mutations of mitochondrial DNA (mtDNA). Blood lactate levels are increased because of a dysfunction in the respiratory chain, with resulting inhibition of the citric acid cycle and accumulation of pyruvate and lactate. Stroke-like episodes have been reported to be associated with other mtDNA mutations. These mutations are point mutations lying within tRNA-encoding genes or within proteinencoding genes, or are deletions encompassing several genes, showing that all these different genetic anomalies can cause a similar dysfunction of the mitochondrion resulting in stroke. Brain imaging can show calcifications of the basal ganglia and focal lesions in the occipital and parietal lobes that are not usually restricted to a vascular territory. NMR spectroscopy detects increased lactate levels. Published therapies include coenzyme Q10, nicotinamide and coadministration of cytochrome c, vitamin B1, and B2.