In this paper we will reconsider Julius Klaproth’s (1783-1835) writings on the Korean language and script as well as the role the medical encyclopedia Tongui pogam played in this context. For the first time in European scholarship on Korean, Klaproth drew heavily upon East Asian sources besides Western ones. We will argue that Ogura Shinpei (1929, 1938) was indeed correct in assuming the unnamed “medical work printed in Korea” Klaproth relied upon for his glossaries of Korean to have been an exemplar of Tongui pogam. The same source is then also what underlies part of his accounts of the Korean script. However, it can be demonstrated that Klaproth’s immediate source must have been a Chinese reprint rather than an actual Korean edition of that work, thus providing a ready explanation for a number of errors found in his writings. Under close scrutiny Klaproth’s publications alone already suggest such a conclusion. Additional evidence - for both the role of Tongui pogam in general and for the involvement of a non-Korean reprint in specific - now comes from a hitherto largely unnoticed letter among his correspondence with the Humboldt brothers, appended to which is a list of Korean words and phrases obviously extracted from the same medical work.