Ranunculus lingua is an Euro-Siberian vascular plant species of freshwater habitats. Distribution and vegetation preferences of this rare species, which is native to the Slovak flora, have not yet been critically revised. The present paper aimed i) to provide the first complex distribution pattern of this species in Slovakia and ii) to analyse all available vegetation plots with species occurrence in order to elucidate the variability of plant communities. The distribution data were retrieved from herbarium specimens, literature records and field surveys. Our revision suggests that R. lingua was found particularly in the lowland areas of the western, south-western and south-eastern parts of the country. It was very rare in other regions of Slovakia, and several populations have become extinct due to drainage or habitat destruction. New localities of secondary origin were additionally documented in some human-made habitats. The temporal trend showed a strong decrease in the number of localities in natural habitats, mainly in the hilly and mountainous regions of the Western Carpathians from the 1980s to the end of the twentieth century. R. lingua was recorded in both forest and treeless swamp communities. Vegetation analysis revealed numerous records mainly in eutrophic marshes (Phragmito-Magnocaricetea class), willow and alder carrs (Franguletea and Alnetea glutinosae).