Toxicological investigations of "Yellow Rice" which have been contaminated with various Penicillium species have shown that Penicillium islandicum apart from well-known hepatotoxic mycotoxin, lyteoskyrin synthesizes cyclochlorotine (chloropeptide, CP), which is also hepatotoxic. Isolation of chloropeptide and its chemical characteristics, acute toxicity and biochemical alterations, tissue distribution and excretion, deformation of hepatic cells, and interaction with cytoskeleton filaments are described. It is shown that the hepatotoxicity of CP is inactivated by dehalogenation of CP by the cytochrome P-450 system.