This paper examines the rise and fall of genetic research on the Korean population from the 1960s to the 1980s. The research program, which was mainly undertaken by Korean geneticists who worked at or graduated from the Department of Zoolo-gy, Seoul National University, was inherently nationalist in sentiment. Engaging with the recent literature in Cold War scientific collaboration in population genetics, this paper focuses on the role of transnational exchange in the shaping of this na-tionalist science in South Korea. It argues that the dynamics of opportunistic col-laboration of the Korean geneticists with foreign researchers over three decades was one of the crucial factors in the emergence and eclipse of the research pro-gram. This study will contribute to the previous literature by illuminating the mar-ginal nature of Korean geneticists’ collaboration and their ambivalent attitudes towards collaboration, and suggesting the needs to pay more attention to the mul-tidimensional aspects of transnational exchange during that period.