Covering: July 2004 to June 2005. Previous review: Nat. Prod. Rep., 2005, 22, 196–229

Terrestrial and marine microorganisms as well as marine invertebrates, particularly sponges and ascidians, are well known for their production of structurally diverse imidazole-, oxazole-, and thiazole-containing natural products, many of which show extensive biological potential including antibacterial, antifungal, antiparasitic, antiviral, and antitumor activities. This review, with 186 references cited, gives an account of the chemistry and biology of these biologically significant secondary metabolites.