The issues raised in this paper mainly concern the spatial changes in socio-economic activity in the commercial and service systems of Polish cities, shown on the example of a medium-sized, former voivodship city of Leszno. The results of research on spatial changes in the field of such activities clearly indicate a significant impact of these changes on the quality of life in the city and the effectiveness of protecting its cultural and environmental values. This study is very important in further sustainable planning, both for multifunctional retail and service infrastructure in the functional and spatial structure of housing estates and in the centre of Leszno, as well as for the infrastructure of cities of similar size in Poland and abroad.