This review is a comprehensive survey of acetylenic anticancer agents obtained from living organisms. Acetylenic metabolites belong to a class of molecules containing triple bond(s). They are found in plants, fungi, microorganisms, and marine invertebrates. Although acetylenes are common as components of terrestrial plants, fungi, and bacteria, it is only within the last 30 years that biologically active polyacetylenes having unusual structural features have been reported from plants, cyanobacteria, algae, invertebrates, and other sources. Naturally occurring aquatic acetylenes are of particular interest since many of them display important biological activities and possess antitumor, antibacterial, antimicrobial, antifungal, phototoxic, HIV inhibitory, and immunosuppressive properties. There is no doubt that they are of great interest, especially for the medicinal chemistry, and/or pharmaceutical industries. This review presents structures and describes cytotoxic activities of more than 300 acetylenic metabolites isolated from living organisms.