We describe ethical issues arising in the allocation of civilian medical resources during armed conflict. Three features are significant in the context of allocating scarce resources in armed conflicts: the distinction between continuous and binary medical resources; the risks of armed conflict itself, and the impact of cultural differences on cases of armed conflict. We use these factors to elicit a modified principle for allocating medical resources during armed conflict, using hemodialysis for patients with end-stage renal disease as a case study.