Non medical factors may significantly influence medical decisions in situations of great uncertainty. Triage of a seriously ill patient or a frail elderly to intensive care represents one such situation. Uncertainty as to the patient outcome, limited opportunity to involve him in the decision, time-pressured circumstances and scarcity of the health care resource make the task especially complex. Variability in the provision of life-sustaining treatments at the end of life was observed. Non medical factors were associated with the ICU admission decision. They are organisational, patient-related and physician-related. Physicians' reasons for ICU admission or refusal at the end of life, and how influential non medical factors are on the decision remain unclear. Facilitating triage and ensuring a fair and transparent decision making process are important to improve patient end of life care and to optimize the use of ICU health care resource. Advance care planning and a better understanding of the ICU admission decision process are two promising areas for research.