A clinical case of a 27-year-old patient with distal arthrogryposis of the 5th type - arthrogryposis with ophthalmoplegia, which was combined in a patient with polyneuropathy is presented. To assess tissue respiration (mitochondrial respiratory chain) and other types of metabolism in mitochondria, cytochemical analysis of lymphocytes in peripheral blood was carried out according to A. Pearse's method modified by R.P. Narcissov. The activity of four mitochondrial enzymes involved in carbohydrate metabolism (lactate dehydrogenase), amino acid metabolism (glutamate dehydrogenase), fatty acid metabolism (а-glyce-rophosphate dehydrogenase) and the second complex of the mitochondrial respiratory chain (succinate dehydrogenase) was assessed. A slight decrease in the activity of the enzyme succinate dehydrogenase, which is part of the second complex of the mitochondrial respiratory chain, was determined. The activity of the enzyme а-glycerophosphate dehydrogenase was more significantly reduced, an increase in the activity of lactate dehydrogenase was noted. In the presented observation, along with the typical manifestations of the disease (contractures of the hands and feet, ophthalmoplegia, ptosis of the eyelids, visual impairment), polyneuropathy with impaired sensitivity of the polyneuritic type was revealed. Thus, a patient with polyneuropathy had a hereditary type 5 arthrogryposis disease. Along with the typical manifestations of the disease, polyneuropathy with hyporeflexia and impaired sensitivity of the polyneuritic type was revealed. Secondary mitochondrial disorders were identified, which was the basis for the appointment of energotropic therapy.