The paper reviews data available on euglenophycean algae of the genus Eutreptiella from the Russian waters of East/Japan Sea. Five species (such as E. braarudii, E. eupharyngea, E. gymnastica, E. cf. marina, and E. pascheri) were identified in our study. E. cf. marina and E. pascheri were found for the first time in the fare astern seas of Russia (including East/Japan Sea, Bering and Okhotsk seas). Morphological descriptions of species are based on light and electron microscopical studies and supplied with information on ecology and distribution. Original micrographs of these species obtained by light and electron microscopy are presented. It was established that E. eupharyngea, E. gymnastica, and E. pascheri cause water "blooms" in spring and summer in eutrophic coastal areas of Peter the Great Bay (East/Japan Sea), where their cell concentrations at these periods exceed $1 imes10^6;cells;l^{-1}$.