Alcohol abuse and dependence, referred to as alcohol-use disorders (AUDs), affect 76.3 million people worldwide and account for 1.8 million deaths per year. AUDs affect 18.3 million Americans (7.3% of the population), and up to 40% of hospitalized patients have AUDs. This review discusses the development and progression of critical illness in patients with AUDs. In contrast to acute intoxication, AUDs have been linked to increased severity of illness in a number of studies. In particular, surgical patients with AUDs experience higher rates of postoperative hemorrhage, cardiac complications, sepsis, and need for repeat surgery. Outcomes from trauma are worse for patients with chronic alcohol abuse, whereas burn patients who are acutely intoxicated may not have worse outcomes. AUDs are linked to not only a higher likelihood of community-acquired pneumonia and sepsis but also a higher severity of illness and higher rates of nosocomial pneumonia and sepsis. The management of sedation in patients with AUDs may be particularly challenging because of the increased need for sedatives and opioids and the difficulty in diagnosing withdrawal syndrome. The health-care provider also must be watchful for the development of dangerous agitation and violence, as these problems are not uncommonly seen in hospital ICUs. Despite studies showing that up to 40% of hospitalized patients have AUDs, relatively few guidelines exist on the specific management of the critically ill patient with AUDs. AUDs are underdiagnosed, and a first step to improving patient outcomes may lie in systematically and accurately identifying AUDs.