From the large number of methods used for the storage and conservation of microorganisms, for the long term storage, cryopreservation and lyophilization are more effective. These methods are applied in the Collections of Microorganisms from different countries of the world. In the National Collection of Non-Pathogenic Microorganisms (CNMN) all strains of microorganisms of industrial interest are preserved by the lyophilization method. The aim of the research was to evaluate the viability and stability of yeast strains stored in CNMN by the lyophilization method. As studied object served 7 new yeast strains of the genus Saccharomyces (S. cerevisiae CNMN-Y-31, S. cerevisiae CNMN-Y-32, S. cerevisiae CNMN-Y-33, S. cerevisiae CNMN-Y-34, S. cerevisiae CNMN-Y-35, S. cerevisiae CNMN-Y-36 and S. cerevisiae CNMN-Y-37) of industrial interest, recently deposited in CNMN. The results obtained on the evaluation of the viability and stability of yeast strains, showed that their viability after lyophilization is lower compared to the initial one and differs from one strain to another. The data obtained after lyophilization show a decrease in titer by one order in the case of strains with a viability of more than 86% and with two units in the case of strains with a lower viability between 82 and 83%. Of the 7 strains of lyophilized yeast, only two after the stress endured during lyophilization reached viability values ranging between 82 - 83% (Saccharomyces cerevisiae CNMN-Y-31 and Saccharomyces cerevisiae CNMN-Y-35), the other five have higher and varies between 86 - 92%, which indicates a fairly good index. The best result after lyophilization was obtained in the yeast strain Saccharomyces cerevisiae CNMN-Y-32, a strain used for the production of dry white wines of the Chardonnay variety, and the lowest value was in the strain Saccharomyces cerevisiae CNMN-Y-35 stored as a recommended strain for the production of dry aromatic white wines of the Sauvignon variety.