Clinical case of mitochondrial encephalomyopathy manifested with lactic acidosis and stroke-like episodes was presented. The patient diagnosis was performed in childhood, based on clinical manifestation, and was confirmed with molecular genetic test (mutation m.3243A>G in gene MT-TL1 was revealed). Appropriate patient management required united efforts of different medical specialists with simultaneous administration of different drugs, modulating intracellular energy production. Due to contemporary medical science achievements, life expectancy of patients with mitochondrial diseases increases, and in age 18 such patients should be treated by adult-practice physicians. Due to such pathology rare incidence the adult-practice medical practitioners are insufficiently informed about principles of mitochondrial disease treatment, that has negative influence on patients condition.