This study focuses on the sands, clays, and limestones of the Sarmatian ingression in the southeastern part of the Dnieper-Donets trough. The Sarmatian age of the sediments is confirmed by mollusks, foraminifers, ostracods, and spongiofauna. The Sarmatian ingression is shown to have completely eroded sediments of the Bereka and Novi Petrivtsi regional Stages (Berekian and Novi Petrivtsian) in the territory under study and reflects a specific stage in the geological development of the Dnieper-Donets trough. The debatable questions of the age interpretation of these sediments are discussed. Particular attention is paid to the so-called «problem of the Poltava Stage» in its historical aspect and its influence on the stratification of the Neogene sediments of the research area; the reasons for not recognizing the lower part of the Stage as Sarmatian are discussed.Lithology, thickness, and wide spread occurrence of sands, clays, and limestones of the Sarmatian ingression in the southeastern part of the Dnieper-Donets trough allow us to consider these sediments to be an independent stratigraphic unit in the rank of a Formation. We propose the name «Hubynykha Formation» and provide its first description. The Hubynykha Fm. retains its stable position in all geological sections and overlies sediments of the Paleogene Mezhyhiria regional Stage (Mezhyhirian) with a sharp contact. The lithology of the Hubynykha Fm. within its spread area has been proved to be fairly similar in most cases. The lower part consists of an alternation of clays and sands; the middle part comprises sands with thin interlayers of clays with blocks of very dense siliceous sandstone at the top; the upper part includes sands with interlayers of clays, marls, and limestones with mollusks overlain by gypsum clays. A section near Hubynykha village, Dnipropetrovsk region is described in detail and proposed as a stratotype for the Hubynykha Fm. of the Sarmatian regional Stage of the Northern Ukraine paleosedimentary province. The obtained results will contribute to improvement of the stratigraphic scheme of the region and its legend and facilitate efficient geological mapping and creation of updated paleogeographic maps.