This presentation aims to complicate the history of Japanese military medicine at the time of the Russo-Japanese War (1904-5) by situating it in a global context. Historical accounts on the topic thus far have elucidated how interactions between the "West" and Japan played a significant role in molding military medicine in modern Japan. However, military medicine in turn-of-century Japan was also shaped by exigencies of modern warfare arising from development of a mass army, and technological changes in weaponry. From this point of view, the Russo-Japanese war represents a major step, as it was one of the first large-scale modern conflicts during which combat fatalities incurred during the war were twice as high as disease fatalities. For this presentation, I will analyze interactions between the Japanese and their Western observers during the Russo-Japanese War in order to contextualize them in term of transnational efforts to respond to the concern over the “modernization” of warfare. Secondly, I will focus on some Japanese military surgeons linked to the transnational enterprises. Specifically, I will examine how the Japanese Army Medical Corps and Eijiro Haga embedded themselves in global networks of military medicine in close relationship with the field of wound ballistics and of international humanitarian law. In this way, my findings will shed light on some transnational elements in the history of Japanese military medicine in the decade preceding the advent of the First World War. By studying the mechanism of organizing knowledge as well as framework for war-time medical practice, I will argue that the Russo-Japanese War gave to Japanese experiences a new prominence as an object of investigation, and that Japanese medical officers acted not only as a taker but a maker of transnational knowledge at the critical junction of the world history in which the principles of the civilization and the destiny of the humanity were seen as threatened.