Background:Bacteriophages act only host bacterial pathogen selectively not affecting the normal microflora of the human digestive tract, not causing allergies. Also found that the bacteriophage preparations don’t have taste, smell and preparation technology doesn’t affect the structure of bacteriophage. Using of bacteriophages for treatment is safe and has established that they are very effective against multi-drug resistant bacteria according to conducted clinical studies. In our country is using the Bacteriophage preparate which is based on local strain of Salmonella Typhi. Nowadays there is no research data whether environmental physical and chemical factors can affect the Bacteriophage activity.Aim:To study whether the environment physical and chemical factors might influence on Bacteriophage of Salmonella Typhi.Materials and Methods:In this study, were used the test strains of the Salmonellatyphimurium, Salmonella typhi and Bacteriophage of Salmonella Typhi. All procedures are performed according to Mongolian National Standard MNS ISO 2416-94, 3317-94 and Bacteriophage of Salmonella Typhi.Our study was established that physical and chemical factors: temperature of water bath, chloroform action time interval, procedure to kept biopreparates all can affect bacteriophage lysis activity.Conclusions:Any use of bacteriophages did not reveal any adverse effects. From the Bacteriophage of Salmonella Typhi preparations kept up to 3 years can be isolated bacteriophage strains by our improved method.