The current study is focused on evaluating the status of benthic invertebrates species in the Lower Danube, including Galati, Reni, Isaccea, Ismail, Kilia, Vilcovo during June of 2014 – December of 2014. A complex monitoring of macroinvertebrate biodiversity is important in order to assess the status of aquatic ecosystems and undertake appropriate protection methods. Benthic invertebrates were sampled by standardized hydrobiological methods. The identification of species was carried out by stereomicroscope SteREO Discovery.V8 (Zeiss) and upright microscope Axio Imager А.2 (Zeiss). More than 30 samples of the benthic macroinvertebrates from the Lower Danube were collected during the joint trip in the frame of MIS ETC 1676 project. The macrobenthic invertebrate populations from the sampling stations of Lower Danube showed the highest abundance in quantitative samples, during October, 2014 at station Kilia - 12320 ind/m2 of zoobenthos without mollusks, most of which were Tubificidae – 6720 ind/m2 and Corophiidae 3520 ind/m2 . The highest values of abundance of total zoobenthos was registered during June, 2014 at station Isaccea -15844 ind/m2 , consisting mainly of Lithoglyphus naticoides (Pfeiffer 1828) - 7760 ind/m2 . The maximum values of total biomass in quantitative samples were registered during June 2014 at station Vilcovo – 870.229 g/m2 , out of which 869.2 g/m2 were Unio tumidus (Retzius, 1788), while the lowest - at station Kilia – 0.825 g/m2 . The highest diversity indices in Lower Danube were registered at the station Isaccea - 34 invertebrate taxa: Annelida - 6, Chironomidae-7, Crustacea-9, Trichoptera-2, Gastropoda-5, Bivalvia-2 and other groups. At the station Reni only 5 taxa were found, which is connected with the character of substrate –dense clay, and absence of other substrates convenient for macroinvertebrates. A total number of 50 taxa were registered in the Lower Danube, including a rare species of Mysidae - Paramysis baeri bispinosa (Martinov, 1924), included in the Red Book of R. Moldova. Among the invasive species of macrobenthic invertebrates, the following species were found: Bivalvia – Corbicula fluminea, Sinanodonta woodiana, Dreissena bugensis, Gastropoda – Ferrissia fragilis, Oligochaeta – Branchiura sowerbyi, and Decapoda - Eriocheir sinensis. A species nominated among 100 of the "World's Worst" invaders - Eriocheir sinensis Brachyura, Decapoda), originating from South-East Asia was also found in Izmail (Milne-Edwards, 1853) (09.10.2014) in fishermen catches. The carapace width was 7.5 cm (maximum width for this species is 10 cm). E. sinensis tolerates highly polluted water and occurs in estuaries, lakes, riparian zones, water courses, wetlands, the lack of competition from other species. Burrowing activities of crabs result in damages of dikes and river embankment erosion. In Danube Delta this species was firstly recorded in 1997 and up to 2004 four specimen of crabs were found in fishermen catches. The most abundant invasive species (for Lower Danube) was Corbicula fluminea with 160 ind/m2 (Kilia 09.10.2014). The biological invasions take the second place after habitat destruction as regarding the negative influence on biodiversity, thus a thorough investigation of invasive species and their impact on native species is further required. The saprobic indices Zelinka-Marvan and Pantle – Buck from the lower Danube reached the limit values 2.24-3.41 of β-mesosaprobic - α- mesosaprobic zone, thus being classified to the «II – good» in Galati, Isaccea up to «V – bad» in Kilia, Vilcovo classes of ecological condition.