Abstract This is a historical and ethnographic account of the transformation of Korean medical institutions in the context of national identity building. Focusing on the traditional medicine cabinet, the author discusses intraprofessional and interprofessional conflicts between Korean Oriental medicine and Western medicine. During the period under study, practitioners of Korean medicine institutionalized their practice by emulating the forms and institutions of Western medicine. In the process, practitioners strategically mobilized “science” and “tradition” to secure their epistemic and political power over contending medical professionals. Invoking the colonial experience as a national disgrace and associating it with the ordeal that indigenous medicine had undergone, practitioners homogenized, expanded, and secured their jurisdictional terrain by both appropriating the techniques and knowledge of traditional healers and accommodating values embedded in Western science. For example, contending that acupuncturists and herbalists had been cut off from the current of tradition by colonialism, practitioners reduced these practices to mere technical work and forced them out from the mainstream of Oriental medicine by ensuring that they were never legally recognized as true physicians. Concurrently, when faced with the expansion of Western medicine into some traditional therapies, practitioners resorted to cultural nationalism. They insisted that the theoretical foundations, diagnostic methods, and therapeutic applications of their own tradition could not be replicated by their Western rivals.