The article addresses the problem of depopulating towns in the postwar period (1946–1990) in Poland. The essence of this study is to highlight the problem rather neglected in scientific research on two levels – empirical and explanatory. In the article, a full inventory of towns, which recorded a decrease in population, in the period, was made on the basis of available statistical sources and relating studies on the issues of population. Due to short-term population swings, only the facts related to depopulation that took place in perspective of the designated research sub-periods were taken into consideration: 1946–1950, 1950–1960, 1960–1970, 1970–1980 and 1980–1990. The analysis was made on the basis of the contemporary administrative division of the country into provinces. The primary purpose of the article was an attempt to answer the question regarding the role of depopulation in the socialist period and the possible connotations of this fact, in relation to population loss reported presently in Polish towns. The starting point was, however, a detailed discussion of conditions of urban depopulation in the socialist period. It was recognized that the understanding of this genetically multifaceted problem should form the basis of interpretation to any generalizations made in relation to the past, present and future demographic changes in Poland and other countries. It was also found that understanding the facts connected with demographic development should be a canon of research conducted with reference to the analysed problems. The raised issue of demographic decrease in Polish towns during the socialist period, falls within such an explanatory model.