Operational environmental management of European landscapes requires geographical information which is valid and coherent across national borders and only takes natural boundaries as criteria for ordering. However, when combining GIS data from different countries, national borders appear as artificial breaks in many medium- and large-scale thematic GIS, for example, topographical, geological or soil information systems. Inconsistencies in GIS data can be categorised into three types: (1) country specific deviations, (2) inconsistencies due to different data surveying and management procedures and (3) errors. Some of the inconsistencies, such as national attribute names, can be ruled out by simple modifications of the data models without changing the structure of the national databases themselves. Others, such as soil typologies, have to be addressed by intensified co-operation between national authorities. It is concluded that for practical and financial reasons, pragmatic solutions are required in order to integrate national data into a European framework.