Instrumental methods of investigation were used for the demonstration of changes in the fatty acid composition of F. tularensis, strain 15 Gaĭskiĭ, during cultivation in solid culture medium, storage after lyophilization, as well as changes in the functioning of the system of membrane-dependent enzymes of the respiratory chain and in the permeability of cell wall membranes by water molecules and NADH after lyophilization. A relationship between the survival rate of F. tularensis cells after lyophilization and stimulation of their endogenic respiration with NADH and succinate was revealed. An increase in residual moisture from 6 to 10-12% was found to intensify the process of lipid peroxidation during the storage of lyophilized F. tularensis cells of strain 15 Gaĭskiĭ.