Increasing use of intensive care unit (ICU) resources by an aging population has resulted in a large and growing group of adults who are 'chronically critically ill' , Although these patients have survived acute illness, they are profoundly debilitated and have ongoing serious complications with continued dependence on life-sustaining therapies. Chronic critical illness is not simply a prolongation of acute critical illness, but a distinct syndrome consisting of persistent respiratory failure and significant derangements of metabolic, neuroendocrine, neuropsychiatric and immunologic function , The number of patients in the USA with chronic critical illness is estimated to approach 100,000 . As the population ages and ICU treatments are increasingly offered to older, sicker patients, these numbers will increase. In this chapter, we will discuss the definition of chronic critical illness, the scope of this serious health problem, venues of care, outcomes and symptoms, and issues with communication between the health care team and patients and their families. We will end by reviewing an interdisciplinary approach to managing this challenging patient population.