This article presents several selected economic consequences of the currently changing number of students in towns and cities in Poland, which has become an increasingly significant issue in view of the dramatic demographic transformations going on nowadays. The aim of the study is to analyze the impact of the changes on local enterprises operating in selected sectors of local economies of the academic towns and cities in the country. The results of the analysis confirm the assumption that selected academic towns can be affected not only by depopulation, but also by a decreasing number of students and—in consequence—a decreasing number of small trade and service enterprises. The authors conclude that co-incidence of these issues can pose a serious threat to local economies, especially where rapid negative economic and demographic changes have already been observed. The changes presented can be treated as the major threat to further sustainable development of Poland.