The structural elucidation of the minor carotenoid sulfates from the marine sponge lanthella basra is discussed in context with the structure assigned to the major sulfate bastaxanthin (c; 3,19,17"-trihydroxy-7,8-didehydro-fJ-~-carotene-3", 6" dione 3-sulfate). Plausible structures are assigned to other bastaxanthins (b, b 2, c 2, d, e and f) on the basis of electronic, IR, 1H NMR, mass and CD spectra, electrophoretic behaviour, chemical derivatization and enzymatic or acid-catalysed hydrolysis. The minor sulfates represent structural variation in the cyclopentane end group with different oxidation levels. Bastaxanthol b (desulfated bastaxanthin b) was a minor carotenoid constituent of L basta. Including tentative chiralities, the structures favoured for the bastaxanthins are: c2, (3R,3'R,5"R)-3,19,3'-trihydroxy-7,8-didehydro-~,x-caroten-6'-one 3-sulfate; b 2, (3R,3'R,5'R)-3,19-dihydroxy-7,8-didehydro-~,x-carotene-3",6'-dione 3-sulfate; b, (3R,1'R,5'R)-3,19-dihydroxy-3',6'-dioxo-7,8-didehydro-f],~-caroten-17'-al 3-sulfate; d, (3R, l'R,3"R,5'R)-3,19,3',17'-tetrahydroxy-7,8-didehydro-f3,~-caroten-6'-one 3-sulfate; e, hydrogen (3R, l"R,5'R)-3,19-dihydroxy-3',6'-dioxo-7,8-didehydro-ft,x-caroten-17'-oate 3-sulfate (?); and f, hydrogen (3R,1'R,3'R,5'R)-3,19,3'-trihydroxy-7,8-didehydro-6'-oxo-f],x-caroten-17'-oate 3-sulfate; for bastaxanthol b (3R,1'R,5"R)-3,19-dihydroxy-3',6'-dioxo-7,8-didehydro-fJ,x-caroten-17'-al. The bastaxanthins are considered as metabolic products of L basta, diadinoxanthin of phytoplankton origin representing a plausiable precursor.