Delirium is a common disorder in hospitalized patients, nevertheless it is poorly recognized by physicians and nurses, even when screening instruments are used. Electroencephalography (EEG) appears to be a sensitive tool for the diagnosis of delirium. However, standard EEG recording with 25 electrodes is labor intensive. We have previously showed that a brief EEG registration with three electrodes and automatic processing can distinguish patients with delirium from patients without delirium very well. However, these findings need to be validated in an unselected population.