Agitation is a psychomotor disturbance characterized by a marked increase in motor and psychological activity in a patient. It occurs very frequently in the intensive care setting. It may be isolated, or accompanied by other mental disorders, such as severe anxiety and delirium. Frequently, agitation is a sign of brain dysfunction and, as such, may have adverse consequences, for at least two reasons. First, agitation can interfere with the patient's care and second, there is evidence demonstrating that the prognosis of agitated (and delirious) patients is worse than that of non-agitated (non-delirious) patients. These conditions are often under-diagnosed in the intensive care unit (ICU). Consequently, a systematic evaluation of this problem in ICU patients should be conducted. Excellent tools are presently available for this purpose. Treatment, including prevention, must be undertaken without delay, and the ICU physician should follow logical, strict and systematic rules when applying therapy.