In medicine, racial differences are frequently presented as part of the best explanation of differences in the risk of diseases. The problem of using racial classification in biomedical research has become important because of its ethical consequences in society. However, the biological relevance of the concept of race cannot be established by any ethical argument and the epistemological role of racial categorisation requires clarification. In this paper, different issues related to the concept of race are considered. This paper analyses the semantic problem concerning the definition of race, considers the ontological problem of race, drawing attention to the biological evidence for genetic differences among human groups, and presents a promising epistemological approach to the problem of race. The purpose of the paper is to examine whether, or when, racial categories belong in biological explanations. It shows that the concept of race cannot be justified in biology because it does not lead to successful predictions, and that genetic discontinuities are sufficient to explain differences in diseases but not needed in the explanation. The biomedical field should search for genetic patterns related to diseases, and should not assume racial discontinuities among human groups and use racial clusters as proxies for undetected genetic patterns.