Abstract The 17th International Conference on Organic Synthesis (ICOS 17) was held in Daejeon, Korea during 22-27 June 2008 under the joint chairmanship of Prof. Eun Lee (Seoul National University) and Prof. Sunggak Kim (Korean Advanced Institute of Science and Technology). Professor Sung Ho Kang (Korean Advanced Institute of Science and Technology) acted as Chair of the Organizing Committee for the event, which is the latest in a regular biennial series that was initiated in 1974 under the auspices of IUPAC. On this occasion, the Korean Chemical Society acted as cosponsors, and the Conference enjoyed generous financial support from the Korean Research Foundation, the Korean Federation of Science and Technology Societies, and a sponsorship club representing Korean industries. Almost 1000 participants, including 412 foreign scientists, attended from 32 countries, once again demonstrating the ongoing international appeal and topicality of organic synthesis. The scientific program of ICOS 17 was characterized by in-depth coverage of many familiar aspects of the topic, such as synthetic methodology, natural products synthesis, bioorganic chemistry, chemical biology, organic materials, and medicinal chemistry. The program was delineated in five broad themes entitled: - Discovery of new reagents and reactions - Challenges and new trends in natural products synthesis - Prospects in bioorganic chemistry and chemical biology - Visions in organic materials researches - Events in drug discovery and process development A total of 51 invited lectures were delivered; in addition to 36 from academia, 13 emanated from industry and 2 from research institutes. A highlight of the lecture program was the Thieme-IUPAC prize lecture presented by Prof. Dean Toste (University of California, Berkeley, USA). The poster program was particularly well supported, and no less than 533 posters were presented during two sessions. This issue of Pure and Applied Chemistry comprises a collection of 12 papers based on lectures delivered at ICOS 17. The organizers are particularly grateful to all who contributed to this issue for their timely efforts. The topics of these papers feature some of the major themes of the conference and thus furnish a representative insight into the scientific program and capture exciting new developments and trends. This series will continue in Bergen, Norway on 2-5 August 2010, and it is confidently expected that it will continue to fulfill an important scientific role in highlighting ongoing advances in modern organic synthesis. Sang-gi Lee Conference Editor