Abstract <p>Acid tephras of different origins and ages are found in late Cenozoic sediments in the Okhotsk-Kolyma Region. The tephra are widespread and occur in many facies and environments such as watershed soils, river and glaciofluvial terraces, and lacustrine and glaciolacustrine sediments. At present, early the Holocene and late Pleistocene tephras have been rather well-studied. New data are available about their distribution, composition and ages. Also, basic morphologic types of tephra deposits and individual horizons have been determined, and their volcanic sources identified. Those unique tephra deposits, which occupy large area and have high concentrations of volcanic ashes, are of a peculiar research interest. These are 0.2–15.0 cm thick layers and lenses of tephra of early Holocene age found in soil horizons, peats and lake bottom sediments throughout the territory of about 80 000 km². Late Pleistocene tephras form lenses of varved limnic kame sediments 500–700 m long and up to 30 m thick in glaciolacustrine sedimentary beds.</p>