Treatment of anxiety and delirium, provision of adequate analgesia, and, when necessary, amnesia in critically ill patients is humane and may reduce the incidence of post-traumatic stress disorders. Injudicious use of sedatives and paralytics to produce a passive and motionless patient, however, may prolong weaning and length of stay in the intensive care unit. This report reviews indications and choices for pharmacologic treatment of anxiety, delirium, agitation, and provision of anesthesia in critically ill patients. The choice of pharmacologic agents is made difficult by complex or poorly understood pharmacokinetics, drug actions, and adverse effects in critically ill patients. Advantages, adverse effects, and limitations of drug treatment, including use of neuromuscular blocking drugs and use of sedatives and analgesia during the withdrawal of life-sustaining measures are reviewed.