Abstract <p>This article presents the results of a study of the qualitative and quantitative composition of several groups of microfossils (diatoms, radiolarians, benthic and planktonic foraminifera, tintinnids, and probably their cysts, papulifères) in surface sediments of the East Siberian Sea (ESS) shelf and the southwestern part of the deep-sea Podvodnikov Basin (PB) adjacent to the continental slope (Arctic Ocean). The distribution pattern of the studied microorganism groups in the sediments made it possible to identify assemblages of these groups and combine them into three taphocoenoses, that is, of the inner shelf (18–45 m), the outer shelf (57–104 m), and the southwestern PB slope (1985–2546 m) (the depth ranges are based on available data). Each taphocoenosis is characterized by a unique set of microfossils and reflects the environmental conditions in which it has formed. The taphocoenosis of the inner shelf differs between the western and eastern taphocoenoses of the shelf due to the influence of different hydrological factors (circulation, river runoff, etc.). These results serve as a basis for monitoring environmental and oceanographic changes in the studied region of the modern Arctic and for paleoreconstructions.</p>