The Eurasian Basin, ~2000 km long and ~900 km wide, consists of abyssal plains of Nansen and Amundsen Basins separated by mid-oceanic Gakkel Ridge. The magnetic field of the Eurasian Basin consists mostly of linear magnetic anomalies (LMA). According to classic hypothesis, anomalies of Cenozoic sequence, from LMA 24 (chron 24, ~53 Ma) to present, were identified and dated. Steady decline of spreading velocity from 22-27 mm/yr. to 5-9 mm/yr. was established for 53-20 Ma interval; later it grew slightly to 7-12 mm/yr. At the same time pronounced asymmetry of geological, morphological and bathymetry features of the abyssal depressions, as well as demonstrated by seismic data asymmetry of distribution and thickness variations of sedimentary formations inside them, lead us to conclusion that the considerable part of the Eurasian Basin was probably formed in pre-Cenozoic time.