This review covers the marine natural products literature for the year 2000 and is organized phylogenetically, with sections on marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates, echinoderms and miscellaneous marine organisms. There is an emphasis on new structures, stressing their biological activities, source organisms and countries of origin, and also syntheses that confirm the structures of known compounds. The review contains 869 structures and 592 references, of which 434 appeared between January and December 2000. Covering: 2000. Previous review: 2001, 18, 1.