A disaster is characterized by an imbalance between needs and supplies. In circumstances in which there occur mass casualties, it is not possible to provide care for all of the victims. Thus, it may be necessary to triage the casualties according to pre-established priorities. The performance of triage is associated with many ethical issues. Currently, no Europe-wide agreement on triage and ethics exists. One system based on a categorization into four groups is proposed. Triage should be avoided whenever possible, but, when it is required, there is an obligation to respect human rights and the humanitarian laws, especially with reference to the Geneva Convention of 1864 and the Universal Declaration of Human Rights of 1948. The condition of informed consent must be followed, even in mass casualty situations. Triage always must follow established medical criteria and cannot be based on any other principles. Triage implies constant re-evaluation of victims as conditions of the victims and of available resources change continuously. In order to facilitate international coordination and cooperation, a universal classification system must be adopted.