Riverine floodplains are among the most biologically productive and diverse, yet threatened, ecosystems in Croatia. In this paper we investigated the water beetle community of the riverine floodplain Odransko polje from April to September 2011 on 9 study sites, 4 temporary and 5 permanent aquatic habitats. On the chosen stations the density and composition of the aquatic vegetation, the durability and type of habitat, the type of bed and the basic physical and chemical parameters of the water (temperature, pH, dissolved oxygen concentration and electrical conductivity) were mesured. The composition of the assemblages was observed by following the overall species richness, abundance, diversity and evenness using Shannon and Simpson diversity indices and Pielou’s evenness index. Various methods were applied in the data analysis. A total of 2982 collected specimens of water beetles were divided into 8 families and 76 taxa. Dytiscidae was the dominant family with respect to species diversity (35 species) and abundance. The highest species richness was recorded for the study site Jezera, pond with permanent water body inhabits with 43 species. Bray–Curtis cluster analysis clustered the eight study sites into four cluster groups based upon the habitat types and water permanence. The hypothesis that species richness and abundance is higher in stations where the species richness of aquatic vegetation is greater was successfully proven. The floodplain Odransko polje is one of the richest sites of the region for water beetles with species classified as the most threatened for Europe, thus confirming its importance in the conservation of biodiversity.