The present article examines the material, epistemological, and social dimensions of late nineteenth-century anti-cholera serum controversies that unfolded in Tokyo and Berlin. It seeks to shed light on the conflicting values embedded in the construction of scientific evidence during the transnational exploration of bacteriology as an effective response to controlling epidemics. Driven by Japanese health authorities’ initiatives, Japanese bacteriologist Kitasato Shibasaburo participated in the elaboration of bacteriological research oriented toward therapeutic application during his stay in Berlin. This work coincided with (...) the rise of a controversy over anti-cholera serum in relation to the animal experiments conducted by Richard Pfeiffer, a German bacteriologist. After presenting a series of animal experiments and certain clinical cases conducted in Germany, France, and Egypt in the context of the controversies, the article analyzes a therapeutic trial conducted by Kitasato in Japan during an 1895 cholera epidemic. His strategy, bringing new data to the transnational debate through an intensive investment of resources in the trial, provoked criticism from his Japanese and German colleagues. These critics questioned Kitasato’s method and pointed out the low social value of this experimental serum therapy, performed in highly equipped conditions. Through this case study, the present article highlights: a) a strong tension between transnational research interactions among bacteriologists and local medical practices during public health campaigns against epidemics at the turn of the twentieth century; b) the importance of analyzing the interconnected effects of local, national and transnational frameworks of medical science when examining the increasingly intertwined relationships between laboratory science and clinical medicine. (shrink)