In classical Chinese medicine, blood in the urine, stool, or phlegm was a sign of disease in one of the body’s internal organs, not in the blood itself. In the nineteenth century, Chinese authors began to see blood in itself as a potential site of disease. This development was amplified by contact with the west, where blood was seen as the medium and substrate of diseases caused by parasites, bacteria, and nutritional deficiencies. This amalgamation of ideas generated a new body-image and phenomenology, focused on the status of a person’s blood. New herbal therapies for enlivening and nourishing the blood soon competed with cod liver oil and iron tonics from the West; biomedical understandings of blood were reinterpreted within Chinese popular culture; and comparative analyses of blood groups, red- and white-cell counts, and other aspects of blood health were used to measure racial and national fitness. This paper examines the process by which blood became both a metaphor for the health of the Chinese nation and a major theoretical and clinical development within “Chinese” medicine.