Mitochondria are cellular organelles that produce energy in the form of ATP. For this reason, they are called "power stations" or "energy factories". Mitochondria have their DNA. Part of mitochondrial DNA in the process of phylogenesis moved into nuclear DNA. There are 4 types of metabolism in mitochondria: a) Transfer of electrons in the respiratory chain with the formation of ATP and oxygen, b) Fat metabolism with the participation of carnitine, c) Amino acid metabolism, d) Carbohydrate metabolism. There are 2 groups of mitochondrial pathology: Primary mitochondrial pathology is hereditary syndromes caused by mutations in genes responsible for mitochondrial proteins (Kearns-Sayre syndrome, Pearson syndrome, MELAS syndrome, MERRF syndrome, and others). Secondary mitochondrial pathology includes dysfunction of mitochondria as an important link in pathogenesis. Primary mitochondrial diseases are caused by mutations in mitochondrial DNA or nuclear DNA that affect the respiratory chain or mtDNA homeostasis. Secondary mitochondrial disorders have been identified in common sporadic neurological diseases, including Alzheimer's disease, Parkinson's disease, and other pathologies.