Since its establishment in 1950, ZEON Corporation has contributed to the advancement of Japanese industry, as a chemical company focused on the manufacture of synthetic rubber. Some of our specialty rubber products hold 40-70% of the worldwide market share. ZEON's exclusive technology is the source of a number of breakthroughs and continues to contribute to today's polymer industry. In order to maintain the position as a leading company in synthetic rubber business, ZEON strategically planned industrialization of polyisoprene rubber to compete with natural rubber. The main raw material for polyisoprene rubber is isoprene monomer, which was not yet available on the market. ZEON had to first develop isoprene extraction technology from C5 fraction of naphtha successfully. The issue then was C5 fraction contained only 10-15% of isoprene monomer. In order to reduce the total isoprene monomer cost, we had to utilize other components. The components are 1,3-pentadiene (1,3-PDE), dicyclopentadiene (DCPD), and others. So along with polyisoprene business, we launched the 1,3-PDE resins business and DCPD resins business for adhesives and traffic paints in 1970. To fully utilize these extracted components, we still had to develop unique products using residual 1,3-PDE and DCPD. Our cyclo-olefin polymer business was born from this basic strategy to fully utilize those components. This report discusses the development and current status of cyclo-olefin polymer and its precision molding business, including optical film business, realized by the ZEON's comprehensive utilization of C5 fraction. (C) 2003 Elsevier B.V. All rights reserved.