The Brazilian fauna of adephagus beetles (Hydradephaga) comprised by the families Dytiscidae, Gyrinidae, Haliplidae and Noteridae is represented by 47 genera and 496 species. We present a list of genera and respective number of species occurring in the Brazilian fauna. Idenfication keys are also provided for the genera of the families Dytiscidae, Gyrinidae and Noteridae. (Haliplidae is represented only by Haliplus).
Keys; Genera; Hydradephaga; Brasil