An investigation was performed on the possibilities for an alteration of the total solidification temperature when preserving concentrated salt media (MBM, MEM, 199, HAM), used for the maintenance of animal viruses and cell cultures. It had been established that by the use of dextran 40000, this temperature could be increased with about 20°C. A protection in 3.6% concentration was recommended and the freezing to minus 40°C might be performed directly in the refrigerator for storage. The temperature should not be raised over minus 32°C during the stockage.