For decades, world-wide flora has been mapped to various extents. The growing need for chorological data in scientific and professional disciplines, and especially in preservation of biological diversity, have underlined the importance of defining the distribution of flora, Numerous regional, national and other atlases have been published in past decades, often as a result of internationally co-ordinated activities. Literature, herbarium collections, and the most precise new data generated during field work are being used as sources of chorological data. The fundamental conditions for such work are the existence of well-defined taxonomic and geographical units. While the basic taxonomic units are contained in check-lists and Floras, geographical units are more a matter of methodological issues (application of artificial areas, basic grid units for indirect mapping, real co-ordinates of localities, areas). Selection of a range method depends on many factors: the accuracy of data sources, available staff, mapping area, compatibility with present standards, technological resources, basic maps, etc. The vast amount of data collected by the mapping of national floras needs to be manipulated by well developed computer tools (RDBMS, GIS). The need to map Croatian flora exists. However, its realisation involves many objective difficulties: lack of trained staff, the accuracy of existing data and the standardisation of certain procedures. Existing chorological data are not compatible regarding: taxonomy (lack of recent revision), precision (13 to 50 % of data are Insufficiently precise), updatedness (77 to 86 % of data are older then 51) years), cartographic base, applied geocoding method (real co-ordinate, MTB, UTM grid). Therefore, standardisation of procedures and methods is necessary for the purpose of the manipulation of existing data and collecting new ones. Here, proposed standards for the mapping of Croatian flora have tried to take into account the reality of carrying out such a project under present conditions, as well as compatibility with similar European projects. The proposal defines basic taxonomic units according to the new Checklist of Croatian Flora, method of indirect mapping, for basic geographical units MTB grid squares, standard labels and names for MTB unite (MTB 1/4, 1/16 and 1/64 grid squares for smaller areas), cartographic bases, display of distribution on 1 :4.000.000 maps (Transverse Mercator projection, 5th zone, central meridian at 15), MTB basic square grid and conceptual examples for constructing databases. Standard labels and names, as well as grids of bask UTM squares, geographical regions with names and fixed boundaries are given, to make exchange and accumulation of data easier. In the enclosure there are «blind» maps of Croatia as assistance for the technical applicability of the proposal, also available in other formats and media, including the corresponding Internet service (GIS BioLab) with download facilities.