The Karyological database of the ferns and flowering plants of Slovakia, available on-line, was established and launched with the publication "Chromosome number survey of the ferns and flowering plants of Slovakia" (Marhold et al. 2007). The on-line version of the database will be updated regularly. The database version 1.0 includes 8096 chromosome number records on 2460 taxa (species and infraspecific taxa) and nothotaxa (hybrids), which were extracted from 578 publications and manuscripts. The database includes chromosome number records on all autochthonous and alochthonous species and hybrids of the ferns and flowering plants wild growing in the area of Slovakia, or those cultivated in Slovakia (such data are marked), or those of unknown origin, where the records were based on plant material obtained from the area of Slovakia (e.g. seeds from botanical gardens, forest nurseries, breeding stations, etc.). ... [Information of the supplier, modified]