The purpose of the study is to examine reasons of depopulation of the region and the contribution of migration to the decreasing population. To achieve this goal the author applies the case study and focuses on the district of Siemiatycze and migration to Brussels, Belgium. The description of the migrant profile is augmented by the application of the Webb technique that classifies the counties in the Podlaskie Voivodship and Siemiatycze district according to the rates of birth and outmigration and their implications for the population change. Several conclusions are drawn regarding the migration conditions in Podlaskie Voivodship, including the confirmation of the status of local economy as the primary motive behind migration and the specific labor market structure in Western European EU member countries.