The authors present the experimental results of study of the role played by domestic flies in the spread of cholera causative agents. It was found that cholera microbes survived on the external surface of flies for 5 to 7 days, and in the insect organism--in the course of their whole life. Cholera vibrios underwent no sharp changes in the organism of flies. By means of individual infection method and keeping of flies excluding a possibility. By means of individual infection method and keeping of flies excluding a possibility of repeated autoinfection it was revealed that cholera vibrios could multiply in the organism of domestic flies. The infected insects can discharge cholera vibrios for a long time into the external environment and contaminate food.