The problems associated with polymerization and copolymerization of lactams have been studied at the Department of Polymers for more than 50 years. During past ten years the research activities have been focused on the study of the anionic polymerization of hexano 6 lactam initiated with magnesium compounds, preparation of block copolymers of polyamide 6 and copolymerization of hexano 6 lactam with lactones. Special attention was devoted to the formation of cyclic oligomers in the polymerization of hexano 6 lactam and their chemical and physicochemical properties.