Depopulation, is the process of a decrease in the number of population in rural areas, which poses a serious threat to the existence of smaller establishments and results in considerable areas being left uninhabited. Spatial differentiation as regards the depth of depopulation is connected with territorial deployment of native and immigrant inhabitants of the Opole Voivodeship. The paper attempts to prove that more severe depopulation affects the areas dominated by the autochthonous population as they are characterised by established traditions of going abroad. On the basis of the data obtained from the last two national censuses conducted in Poland in 2002 and 2011, as well as data from the running records, it was possible to assess the size of non-registered migration which – as it has turned out only in the case of a few districts – was a non-registered inflow of inhabitants. Despite the fact that following Poland’s accession to the European Union the immigrant population can participate freely in the process of leaving abroad, the extent of the non-registered outflow is much greater for the districts which are dominated by the autochthonous population.