This study examined research performance of Korean physicists, comparing Korean-authoredpapers versus internationally co-authored papers, indexed in SCI, 1994-1998, and using thenumber of citations received by internationally co-authored papers covered by the SCI CD-ROM.For the study, 4,665 papers published from the researchers affiliated with the physics departmentsor physics-associated laboratories at Korean universities and indexed by SCI were analyzed.Korean authored papers tended to be published in Korean, Japanese, and UK journals, whileinternationally co-authored papers were more likely to appear in German, Dutch, and Swissjournals. Among the 18 authorship countries (on the basis of first author), 93 internationally co-authored papers by U.S. researchers had the highest citation rate, an average 15.9 citations perpaper. Of the eight countries that published over 5 papers, there was no correlation between theaverage number of citations per paper and the total number of citations. However, an ANOVAindicated a significant difference between the average number of citations per paper according tocountry (F = 5.84, p < 0.0005). In other words, papers by the U.S. and French researchers tendedto be cited more frequently than papers by the Italian, Japanese, Korean, Russian, and Germanresearchers.