Fauna of aquatic Coleoptera (Insecta) in Trabzon

495 specimens of aquatic beetles were collected by the the author from Trabzon province in Black Sea region of Turkey between June ? September in 2005 ? 2006. As a result of identification, 27 species group taxa of 16 genera of 5 families belong to the order Coleoptera were determined. In the text, habitats, phenologies and distributional data of the species group taxa were given. Distributional data of each species group taxon were presented two parts as distribution in Turkey and distribution in the world. The species Helochares (s.str.) lividus (Forster, 1171) of the family Hydrophilidae, is reported as the second record for Turkey. Gyrinus (s.str.) distinctus (Aubé, 1836) of the family Gyrinidae, Noterus clavicornis (De Geer, 1774) of the family Noteridae, Ilybius fuliginosus fuliginosus (Fabricius, 1792), Oreodytes davisii davisii (Curtis 1831) and Hydroporus askalensis (Wewalka, 1992) of the family Dytiscidae, Anacaena limbata (Fabricius, 1792) and Coelostoma (s.str.) orbiculare (Fabricius, 1775) of the family Hydrophilidae, Helophorus micans (Folderman, 1835) and Helophorus v obscurus obscurus (Mulsant, 1844) of the family Helophoridae is recorded as the first time for the Black Sea region of Turkey. In addition to this, 15 determined species group taxa are new fort the research area.