Research of macrophyte vegetation of the artificial water reservoirs was carried out during the vegetation season of 2008 in the Krupinská planina Mts. (southern part of central Slovakia). Twenty-one reservoirs were studied and twenty plant communities from the Lemnetea, Potametea and Phragmito-Magnocaricetea classes were found. Potametum acutifolii is a new aquatic community for the territory of Slovakia that was found in the reservoir near Hrušov village in intermediately deep, slightly alkaline water with a relatively low content of soluble mineral matters, a high water transparency and a silt-clay sediment on the bottom. Moisture was the main environmental gradient of the studied vegetation explained by Ellenberg's indicator values. Species richness was significantly negatively correlated with water depth. The correlation between the area of reservoirs and the number of detected plant communities was weak and non-significant. Changes of macrophyte vegetation were studied on the case of three reservoirs. Detected changes were caused mainly by human activities or water level fluctuations within the studied period. Raziskave makrofitske vegetacije umetnih vodnih smo izvedli v vegetacijski sezoni leta 2008 v hribovju Krupinská planina (južni del osrednje Slovaške). Raziskali smo enaindvajset vodnih teles in našli dvaindvajset rastlinskih združb iz razredov Lemnetea, Potametea in Phragmito-Magnocaricetea. Asociacija Potametum acutifolii je nova vodna rastlinska združba, najdena na ozemlju Slovaške. Našli smo jo v vodnem telesu blizu vasi Hrušov v srednjegloboki, rahlo alkalni vodi z razmeroma nizko vsebnostjo raztopljenih mineralnih snovi, z visoko vodno prepustnostjo in muljasto-glineno usedlino na dnu. Glavni okoljski gradient obravnavane vegetacije, kot kažejo Ellenbergove indikacijske vrednosti, je vlažnost. Število vrste je v negativni odvisnosti z globino vode. Korelacija med površino vodnega telesa in številom najdenih rastlinskih združb je bila nizka in ni bila značilna. Spremembe makrofitske vegetacije smo proučevali v treh vodnih zbiralnikih. Opažene spremembe so posledica predvsem človeških dejavnosti ali nihanja vodnega nivoja v obravnavanem obdobju.