Cylindrospermopsin (CYN) is an alkaloid toxin of cyanobacterial origin that is hepatotoxic, cytotoxic, and genotoxic. The CYN toxin family has also been shown to be capable of accumulation in certain aquatic and terrestrial plants, which raises some environmental concerns regarding the potential impact on ecological systems. CYN has the ability to cause irreversible inhibition of protein synthesis, cellular necrosis, deoxyribonucleic acid fragmentation, and mutagenesis. CYN possesses a zwitterionic tricyclic guanidine moiety with a sulfate ester functionality that is combined with a hydroxymethyluracil. Some organisms that feed on cyanobacteria have the ability to concentrate high levels of toxins in vivo. In vitro chromosomal effects may suggest CYN is a spindle poison or can damage the centromere/kinetochore function; the mechanisms involved are unknown. Human intoxication produces various gastrointestinal symptoms after initial exposure, and in the case of exposure to high toxin levels, kidney malfunction and death may occur. Human intoxication can occur after drinking contaminated domestic water and from eating contaminated fish.