Afflicting as many as 80% of critically ill elderly (older than 65 years) patients, adverse psychologic reactions (e.g., acute confusional states) to critical illness and its treatment present a unique challenge to medical and nursing intensive care practitioners. Additionally, the consequences of these adverse psychologic reactions financially strain health-care organizations, placing additional constraints on the delivery of health-care services. This article presents information regarding the origins of these adverse psychologic reactions and nursing strategies for the prevention, identification, and management of these clinical states. With such information, nurses who work in critical care units may be better equipped to identify and care for patients at risk of or experiencing an adverse psychologic reaction to critical illness