ABSTRACT: Antifreeze glycopeptides and peptides have been isolated from 37 species of Antarctic fish representing the families Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae, Muraenolepididae, Liparididae, Zoarcidae and Myctophidae. Amino acidand carbohydrate analysis as well as antifreeze activity indicate that all investigated notothenioids contain antifreeze glycopeptides (AFGP). Pleuragramma antarcticum, Lepidonotothen kempi, Bathydraco marri and Dolloidracolongedorsalis synthesize additional antifreeze molecules. The non-notothenioid species possess antifreeze peptides (AFP), except Muraenolepis marmoratus and Macrourus holotrachys, which possess a glycosylated antifreeze peptide similarto the AFGP found in the notothenioid species. A novel glycopeptide comprised of the carbohydrate residue N-acetylglucosamine and the amino acids asparagine, glutamine, glycine, alanine, and traces of arginine, valine, leucine and threonine was isolatedand characterized from P. antarcticum. The level of antifreeze concentration was dependent on the ambient water temperature, the depth of catch and life cycle of the species. Antifreeze activity of AFGP varies between 0.52 (Neopagetopsisionah) and 1.20*C (P. antarcticum) at a concentration of 20 mg ml^-1. Antifreeze activity of AFP is lower than 0.50*C. A linear increase in activity of the AFGP could be demonstrated concomitant with decreasing ice content. Thestructural diversity of antifreeze molecules and their occurrence in a wide range of Arctic and Antarctic fish species suggest that they evolved from precursor proteins before the continental drift and recently during Cenozoic glaciation into the variousantifreeze molecules.