Russian Scientific Center of Surgery named after B. V. Petrovsky has an experience of 30 orthotopic heart transplantations with the maximum follow-up 25 years. Nine patients survived 11-year period after operation, of those in 6 during long-term period of 11-25 years we studied ultrastructural assessment of cardiomyocytes of the donor heart. This article provides the results of mitochondrial particles: the data witnesses on the increase of destruction in mitochondria with time that finally leads to energy deficit of cardiomyocytes and progression of post-transplant cardiomyopathy.