Mirna Valley was odonatologically poorly studied with 37 species recorded up to 2015. The purpose of the master's thesis was to study the diversity of the dragonfly fauna in the area of the Mirna Valley and evaluate the adequacy of the current Natura 2000 areas for Coenagrion ornatum and Cordulegaster heros that are listed in the Annex of the Habitats Directive. During the survey 47 field days were conducted in the years 2015 and 2016. We collected data on the presence of 47 species of dragonflies at 119 sampling sites. We confirmed the presence of all the previously known species and recorded ten new species: Lestes barbarus, Lestes dryas, Sympecma fusca, Coenagrion pulchellum, Ischnura pumilio, Aeshna affinis, Aeshna isoceles, Brachytron pratense, Epitheca bimaculata and Sympetrum meridionale. We confirmed the reproduction of 40 dragonfly species in the Mirna Valley. Coenagrion ornatum has one of the strongest populations in Slovenia in the Mirna Valley, however Natura 2000 areas do not include its whole distribution area. For the species we defined the most important nature conservation areas according to the density of adult specimens and the confirmed reproduction. Cordulegaster heros is frequent in the influent streams and in the upper part of the river Mirna. With 32 recorded dragonfly species the fish pond Blato has one of the highest diversity of dragonfly species in Slovenia.