This research is aimed at establishing hierarchy of town settlements considered here as the most important centres of services for population. Identification of principal components of service system and recognition of its internal structure in the area of Dolne Powisle (Lower Vistula Land) is potentially significant for any attempts of verification of territorial structures consequent upon the administrative reform introduced in 1999. Hence, this research is of some applied importance. Beside pure and applied aspects of this work, the methodology used is also worth emphasising. The new approach to the issue of centrality is suggested, in which the index of centrality is based on the criterion of employment. Within the total employment in central activities in each town the part related to services for population of town's hinterland has been distinguished and called 'central employment'. The level of centrality is shown by surplus of functional importance, i.e. by the level of central employment (Vc). This approach follows the methodology of analysis of economic base. The following conclusions have emerged from this study: 1. The level of centrality generally reflects the size of a town, hence the correlation between these two characteristics is high. However, some deviations may be recognised if centrality is analysed relative to the size of population. Higher centrality per capita is typical for large and medium-size towns, which are (or were) administrative centres or are not specialised. 2. A factor of locality exerts significant control upon the rank of the town and its function as an area of services. If located close to a larger and stronger competitive town, functional degradation may occur, which is described as a 'shadow of big city'. It manifests itself in the decline of selected standard functions in favour of more specific ones. Also, in many cases the localisation factor determines a low level of centrality of towns lacking their own rural hinterland, hence left without an area to provide services for. 3. In the study area 3 regional centres and 43 sub-regional centres have been distinguished, of which 38-39 fulfil the criteria to be county ('powiat') capitals. As far as county towns are concerned, a distinct agreement between empirical results of this research and principles of administrative reform introduced in 1999 has been found. 4. The group of sub-regional centres (county capitals) is represented, almost entirely, by towns were county capitals prior to the 1975 administrative reform. This points to durability of service function, but also to absurdity of the decision made in 1975 to abolish counties as administrative units. 5. Absence of clear functional hierarchy within the group of biggest towns indicates that the area under study is not a uniform functional region. The occurrence of three centres of regional importance allows one to conclude that the Lower Vistula Land encompasses more than only one area of region type. 6. Gdansk shows the highest level of centrality, yet its supremacy over Bydgoszcz and Torun is not high enough to consider it as a superior city. Moreover, the peripheral location of Gdansk in relation to the southern part of the area coupled with insufficient accessibility, orientation towards maritime economy, and weak functional links of standard type, do not predestine Gdansk to be the capital of the entire region. 7. Bydgoszcz and Toruń are two competing cities of similar level of centrality within the area occupying the central part of the triangle outlined by cities of Poznań, Gdańsk and Warszawa. Supremacy of Toruń as far as functions of higher rank are concerned (higher education) is shown, but this is balanced by similar relative weights of each component of centrality, i.e. regional, sub-regional, and local functions, in the case of Bydgoszcz.