Mitochondrial diseases (MD) make up a heterogenous group of pathological conditions characterized by disordered intracellular energy metabolism due to genetically determined disturbances of oxidative phosphorylation. Brain and muscles are most frequently affected in MD. Its systemic manifestations include cardiac (cardiomyopathy, arrhythmia), endocrine (diabetes), gastrointestinal, and renal disorders. This review focuses on neurologic symptoms of MD, such as stroke-like episodes (SLE) in patients with mitochondrial encephalopathy, lactic acidosis (MELAS), and ischemic stroke associated with mitochondrial cardiomyopathy and occlusive arteriopathy of main intra- and extracranial vessels. Clinical features and pathogenesis of SLE are considered along with related morphological changes in the brain, methods of laboratory and instrumental diagnosis and approaches to treatment. Mitochondrial respiratory chain and mechanisms of its' dual genetic control by nuclear and mitochondrial genomes are briefly described. Peculiarities of MD inheritance are discussed.