The intersectoral and interdisciplinary nature of health promotion gives rise to ethical questions. This is because health promotion depends upon alliances between people who often have different perspectives on what matters in particular cases or different visions of the good society. This paper draws on the ambivalent relationship that health promoters can have with biomedicine to illustrate and explore the nature of these ethical questions. Examples from everyday life are used to underline the familiar nature of the kinds of coalitions and compromises that are needed to work alongside others with different values to oneself. It is suggested that analogous kinds of compromise are needed in health promotion and that this requires a form of ‘diplomatic ethics' for health promoters that, in turn, raises questions about their ethical integrity.