The growing involvement of anthropologists in medical humanitarian response efforts has laid bare the moral and ethical consequences that emerge from humanitarian action. Anthropologists are well placed to examine the social, political, cultural and economic dimensions that influence the spread of diseases, and the ways in which to respond to epidemics. Anthropologists are also, with care, able to turn a critical lens on medical humanitarian response. However, there remains some resistance to involving anthropologists in response activities in the field. Drawing on interviews with anthropologists and humanitarian workers involved in the 2014-2016 West African Ebola epidemic, this paper reveals the complex roles taken on by anthropologists in the field and reveals how anthropologists faced questions of legitimacy vis-à-vis communities and responders in their roles in response activities, which focused on acting as 'firefighters' and 'cultural brokers' as well as legitimacy as academic researchers. Whilst these anthropologists were able to conduct research alongside these activities, or draw on anthropological knowledge to inform response activities, questions also arose about the legitimacy of these roles for anthropological academia. We conclude that the process of gaining legitimacy from all these different constituencies is particular to anthropologists and reveals the role of 'giving voice' to communities alongside critiquing medical humanitarianism. Whilst these anthropologists have strengthened the argument for the involvement of anthropologists in epidemic response this anthropological engagement with medical humanitarianism has revealed theoretical considerations more broadly for the discipline, as highlighted through engagement in other fields, especially in human rights and global health.