We report about the Early Miocene Tagay fauna of Olkhon Island, the largest island of the Baikal Lake. The Tagay fauna is of high scientific importance because of the diversity of fishes, amphibians, lizards, snakes, turtles, manifold birds and mammals. The lithology, geochemistry and the fossil record along the Tagay-1 section allow reconstruction of various palaeoenvironments, i.e. open water, shallow lakes with adjacent wetlands, riverine woodlands, and also forested and dry habitats. The fossil record, lithology and geochemical sediment-analyses suggest a temperate palaeoclimate with short humid and dry periods. The small mammal record and the magnetic polarity pattern of the upper part of section Tagay-1 correlate with the subchrons C5Cn.2r – C5Cn.1r of Chron C5C and the late Burdigalian Stage of the Geologic Time Scale (GTS2000). The corresponding age range of the Tagay fauna is ~16.5 to ~16.3 Ma.