The chronically critically ill are a challenging population of patients. Their mortality rate is high and expected functional status is low. The physician responsible for the care of these patients often is conflicted because the gains experienced by these patients may be small or absent whereas the pressure by society to use medical resources better is great. This pressure leads to the need for making difficult decisions on issues ranging from the initiation of acute care to withholding and withdrawing of care at the end of life. By understanding the ethical principles that govern decision-making, the physician can guide patients and their families toward realistic expectations.