The mental status evaluation is a useful test in the emergency department. The major purposes of the examination are to determine the presence of neuropsychiatric illness and to determine whether this illness is functional or organic. The most accepted evaluation of mental status is the formal mental status evaluation. This extensive test is rarely necessary in the emergency department; rather a short test of cognitive function, such as the Cognitive Capacity Screening Examination or Mini-Mental Status Examination, may be more appropriate. With frequent repetition in use and the concomitant development of clear standards for interpretation of the examination used, the emergency physician will become more comfortable with bedside mental status testing.