During the expedition aboard RN Pavel Gordienko (September, 2002) investigations in the Japan Sea areas at which radioactive wastes were disposed of the former Soviet Union have been conducted in order to assess the present level of radioactive contamination of the marine environment. Concentration of Cs-137, radioecologically one of the most important radionuclides, in near bottom sea water and seabed sediments were found to be low, 2.8-17.2 Bq/m(3) and 3.2-27.2 Bq/kg dry weight, respectively, which do not differ significantly from the levels elsewhere in the northwest Pacific Ocean, arising from global fallout Results of measurements were compared with results of Joint Japanese-Korean-Russian expedition to the Sea of Japan in 1994, 1995 y.