The problems of transition to the new national coordinate system are discussed. The stress is laid upon the transformation of various spatial databases of the Surveying and Mapping Authority of the Republic of Slovenia. The ways of transformation between the old and new national coordinate systems and problems with the inhomogeneous accuracy of the old system are presented. The main goal of the paper is the presentation of transformation models with metre and decimetre levels of accuracy – the so called simple and complex models. These are the proposed transformation models that originate from the empirical knowledge on the Slovene national coordinate system. Analyses of consequences of various transformations for spatial data (e. g. areal distortions) have been carried out. The proposal of implementation of transition to the new coordinate system for spatial databases is presented. The course of events isdetermined for each of the spatial database. They are distinguished between two models according to the way of maintenance and the required accuracy of transformation. Some specific demands on theparticular databases were also discussed. Finally, the transformation of orthophoto – the first database that has already been transformed into the new coordinate system – is presented.