The microdistrict principle of urban environment organization, developed in Soviet urban planning, formed a certain configuration of the placement of trade and services. However, the market transformations of the 1990s dramatically affected both the number of retail facilities and their location. The purpose of this research was to identify the effects of retail development for the functions and morphology of the microdistricts of Soviet construction. The work is based on empirical materials on St. Petersburg, where research was conducted based on the study of telephone books in the late 1980s, and field mapping of selected areas of the city. It was found that at the moment there was a rapprochement of the retail functions of the areas of mass housing construction and the historical center. The number and density of everyday demand objects in microdistricts increased many-fold, while goods and services of periodic demand came out on top in terms of the number of objects. Retail of episodic demand has ceased to obey the center-peripheral principle in placement. The Soviet principle of spatial monopoly was replaced by the principle of spatial competition, which significantly transformed the morphology of urban space.