Research performance in Korea has increased considerably in the past few years, both with regard to relative output of publications and the number of internationally co-authored papers. The purpose of this study is to characterise international scientific cooperation in Korea through the numbers of internationally co-authored papers covered by the Science Citation Index CD-ROM, 1994-1996. A total of 3,627 collaborative papers published in 1,083 scientific journals were selected to analyse papers written in collaboration between Korea and other countries. The data reveal that Korea's coauthorship level with other countries was relatively high, representing 26.8% of national output. Among the collaborative papers, a large majority of the papers (84%) were authored by researchers at universities, while about 10% came from scientists at government-supported institutes and only 6% from industry. The country with the highest rate of cooperation with Korea is the USA (42%), followed by Japan, Italy, Germany, the UK and France. Considering the strong interaction between Korean and American science, economic and political factors appear to play a strong role in the international co-authorship process. The results show clear variation in levels of international cooperation according to the disciplines: technology, agriculture and earth sciences represent local interests, while physics, chemistry and biology are mainstream subjects. 50 1 2