Humanitarian healthcare work presents a range of ethical challenges for expatriate healthcare professionals, including tragic choices requiring the selection of a least-worst option. In this paper we examine a particular set of tragic choices related to the prioritization of care and allocation of scarce resources between individuals in situations of widespread and urgent health needs. Drawing on qualitative interviews with clinicians, we examine the nature of these choices. We offer recommendations to clinical teams and aid organizations for preparing and supporting frontline clinicians in their efforts to determine the least-worst option, and in their responsibility for making such choices.