This review describes the isolation from marine organisms of all secosteroids reported in the literature from 1972 to 2004. Secosteroids are highly oxidized metabolites with bond cleavage in the rings of the steroid tetracyclic nucleus. All secosteroids are grouped in accordance with their ring joined to side chain as 5,6-, 9,11-, 9,10- 8,9-, 8,14- and 13,17-secosteroids and the structures and the synthetic works, where available, are reported. Furthermore, this review gives details on the biological activities of the isolated secosteroids (e.g. antiproliferative, antifouling, antiinflammatory, antimicrobial, ichthyotoxic and antiviral).