Communities of small mammals on the territory of Yakutsk and in its vicinity have been studied. Residential areas, undeveloped sites, suburban zone, and agricultural lands are covered. A total of 2,736 cone-days and 525 trap-days are accumulated and 388 specimens of small mammals from 13 species belonging to Rodentia and Eulipotyphla orders are collected. The abundance of small mammals in different types of environment have varied from 2.2 to 22.9 individuals per 100 cone-days. The highest values of species diversity are found in the suburban zone in the areas of surviving natural biotopes. The zone of the city’s residential areas is characterized by the lowest abundance and species diversity of small mammals, primarily Eulipotyphla, and also by the presence of eusynanthropicMus musculus and Rattus norvegicus. The undeveloped territories of the city are characterized by a high total abundance of small mammals, but poor community composition, which is close in its structure to floodplain biotopes. Communities of agrocenoses are also poor, due to elimination of forest species, and characterized by uneven distribution of small mammals among the biotopes. On the whole, the anthropogenic effect of urbanization is manifested in poor composition of communities and changes in the dominance structure. The appearance of the house mouse in the zone of detached housing indicates intensifying urbanization of the territory and ongoing synantropization of the fauna.