ENDemographic potential is a particularly important consideration in border areas that are peripheral regions of a country. The aim of this study was to identify differences in the quantitative demographic potential of Polish–German and Polish–Lithuanian transborder regions, as well as the extent to which natural population increase and net migration influence the demographic potential of border regions. An essential element of the research was the analysis of the importance of borders on shaping the quantitative demographic potential. The study relied on the zeroed unitarization method and the method proposed by Webb. The study revealed considerable spatial variation in the quantitative demographic potential of the analyzed regions at LAU 1 (Local Administrative Units) on the background of NUTS 0 (Nomenclature of Territorial Units for Statistics) and NUTS 2. The highest values were noted in urban units, which accounted for 11.0 % of all evaluated units. The areas characterized by the lowest demographic potential represented 16.5 % of the total number of the analyzed units, which should be regarded as a positive outcome. Most of these border regions were situated in Germany and Lithuania. Demographic potential is an important determinant of social and economic growth; therefore, the results of this study can be used to diagnose problems in border regions and implement the required regional policies. Keywords: demographic potential; natural population increase; migration; Polish–German transborder regions; Polish–Lithuanian transborder regions. [From the publication]