The article examines the population dynamics in Odesa during the XIX century. The source base was the archival material of State archive of Odesa region which allowed us to consider the specifics of this process. It is noted that in the first half of the XIX century the number of urban residents increased dramatically due to their mechanical growth. This is caused by a significant number of immigrants from various regions of the Russia Empire and some European countries who were attracted by the city’s economic development opportunities. It has been proven that the natural increase of the population began to grow only in the second half of the XIX century. However, even in this period, the process took place quite slowly. The reasons were, for the most part, high infant mortality, caused by unsatisfactory living conditions of a certain part of the population and frequent epidemics. Only at the end of the century there was a certain improvement in the living conditions and medical care of the population, which had a positive effect on the solution of the mentioned problem. At that time, the dominant factor in the growth of the number of city residents was natural growth, which testifies to the significant socio-economic and cultural development of Odesa.