Based on organized long-term research of biodiversity of Ephemeroptera in the Labe, Morava and Odra river basins in the Czech Republic, distributional maps of all species ever found in this territory are presented. Altogether more than 5, 000 evenly distributed localities covering all types of aquatic biotopes and all altitudinal zones have been investigated in all seasons in the 1950's, 1970's, 1980's and recently. The maps showing historical and actual distribution of individual species are arranged according to the uniform grid system currently used in entomofaunistics in Europe are constructed for altogether 98 species of the order including 3 evidently extinct species and one species of incertae sedis. Commentaries to these maps are directed to the type of life cycle, biotope and habitat preference of larvae, abundance, altitudinal range, density of localities of occurrence in the area investigated and status of species found from the biodiversity protection point of view.