The invertebrates associated with Myriophyllum spicatum L., were studied during the vegetation period in 2004, at three stations I, II and III, in lake Sakadaš within Kopački rit floodplain, Croatia. A total of twenty one taxa were recorded, with the dominance of the insect larvae representatives. Family Chironomidae had the greatest abundance and represented 67% of all recorded invertebrates, while as nematodes and oligochaetes were especially abundant at the third station. Significant differences in invertebrate abundances were recorded between months of sampling – July and August as well as July and September. Also, stations I and II showed statisticaly important differences in relation to station III, located near lake s dam. Physicochemical data, including trophic state indices, as well as invertebrate community composition were indicative for eutrophic state of water with a tendency to hypertrophy at all stations in lake Sakadaš.