Relations between metropolitan core cities and regional and sub-regional centres are part of a broader discussion on the importance of metropolitan areas for the development of regions. These relations are dealt with in this paper in the context of the growth pole theory. The paper focuses on the migration process in relation to enterprises. By moving their businesses, companies contribute to backwash and spread effects. Since company migrations between municipalities occur in both directions, the question remains open as to which migration direction dominates – whether from sub-regional centres to core cities or vice versa. This paper attempts to verify the hypothesis that regional and sub-regional centres in the Mazowieckie voivodship suffer the largest loss of enterprises due to migration to the core city of Warsaw. The results obtained were varied and the hypothesis was confirmed, especially in the case of three cities: Siedlce, Radom and Płock; and partly in the case of Ciechanów.