The present sources of anthropogenic radionuclides in the marine environment, consisting of global fallout, nuclear weapons testing, releases from nuclear facilities, radioactive waste dumping, the Chernobyl accident and nuclear submarine and aircraft accidents, are reviewed. 9 0 Sr, 1 3 7 Cs and Pu isotopes have been chosen as representative of anthropogenic radionuclides to study their distribution and behaviour in the marine environment. The data on their concentrations and inventories in seawater and sediment are presented and discussed. For dose assessment, 1 3 7 Cs and 2 1 0 Po were chosen as they are the most representative of anthropogenic ( 1 3 7 Cs) and natural ( 2 1 0 Po) marine radioactivity on a global scale. The average annual individual doses from ingestion of marine food estimated for the world population for the year 2000 are of the order of 0.03μSv from 1 3 7 Cs and 9μSv from 1 3 7 Cs. The annual dose of 2 1 0 Po for a hypothetical critical group living on the NE Atlantic coast and consuming 100kg of fish and 10kg of shellfish per year would be 3μSv, while the contribution from 2 1 0 Po would be 160μSv. These values are well below the accepted value for the public of 1mSv.