This paper examines the transnational exchanges associated with the emergence of racial blood group studies in Greece. It explores the overlap between anthropological and medical perspectives as well as the concurrences and tensions between national and transnational concerns. By following the work of the main Greek physical anthropologist of the interwar period, the paper asks how politics interpenetrates into this case study in a scientifically consequential way and conversely how innovation in research allows anthropologists to intervene with politically timely questions. It showcases how wartime mobilities generated anthropological data that weaved and strengthened the fabric of the Greek national narrative.