Mutants of Saccharomyces cerevisiae with inactivated endopolyphosphatase gene PPN1 did not grow on lactate and ethanol, and stopped growth on glucose earlier than the parent strain. Their mitochondria were defective in respiration functions and in metabolism of inorganic polyphosphates. The PPN1 mutants lacked exopolyphosphatase activity and possessed a double level of inorganic polyphosphates in mitochondria. The average chain length of mitochondrial polyphosphates at the stationary growth stage on glucose was about 15-20 and about 130-180 phosphate residues in the parent strain and PPN1 mutants, respectively. Inactivation of the PPX1 gene encoding exopolyphosphatase had no effect on respiration functions and on polyphosphate level and chain length in mitochondria.