The article is devoted to the activities of Sanitary Supervision in Moscow during the difficult years of Soviet power (1925-1954). By the beginning of this period, the Moscow Municipal Sanitary Organization already had 40 years of experience, but the new time required new skills and new approaches from sanitary doctors. On the basis of factual material, the author reveals the forgotten pages of the history of Sanitary Affairs: how the Criminal Procedure Code of the RSFSR turned Sanitary Supervision bodies (sanitary doctors) into bodies of inquiry; how in the twenties sanitary doctors assisted the Moscow Council in its struggle for the improvement of the city; how in the thirties the process of formation of the state sanitary inspection took place; how the service participated in preventive Sanitary Supervision during the first five-year plans, when there was a huge gain in industrial production in the capital and the General Plan for the reconstruction of Moscow was implemented; how the sanitary and epidemiological service was created in the pre-war years; what difficult work did sanitary doctors have to do during the Second World War to ensure sanitary and hygienic conditions for contingents moving to evacuation and to carry out preventive measures against the occurrence of parasitic typhus and gastrointestinal diseases; how did they have to conduct sanitary control over the cleaning of the city in conditions of limited transport and maintenance personnel and carrying out new non-removal methods of cleaning the city; how was control over the work of baths, sanitary dispensaries, laundries, equipment and operation of bomb and gas shelters ensured. The final part of the article shows the process of reforming the sanitary service of the capital in the post-war years, which was fully completed only by the mid-fifties of the twentieth century.